The Potential Costs of
Expanding U.S. Strategic
Nuclear Forces If the New
START Treaty Expires
AUGUST 2020
CONGRESS OF THE UNITED STATES
CONGRESSIONAL BUDGET OFFICE
At a Glance
e New START Treaty will expire in February2021unless the United States and Russia agree to extend it for
up to ve years. Expiration of the treaty would end several decades of continuous coverage under arms con-
trol agreements that limit strategic nuclear forces and provide transparency. If the treaty expired in 2021, the
United States and Russia could respond by maintaining the status quo. Alternatively, they could take various
actions to compensate for the lack of treaty limits, perhaps to address a real or perceived buildup of forces by
the other party.
e Congressional Budget Oce was asked to examine what the costs would be if the United States pursued one
type of outcome: increasing its deployed strategic nuclear forces from no more than 1,550warheads as speci-
ed in New START to the levels specied in the three most recent agreements—the Moscow, START II, and
START I treaties. Because forces could be expanded in many ways to meet those levels, CBO looked at a range
of outcomes and their costs.
•
Expanding forces to Moscow Treaty limits (1,700 to 2,200warheads) would not increase the Department
of Defense’s (DoD’s) costs relative to its current plans, which call for elding a new generation of strategic
nuclear delivery vehicles to replace the current generation. CBO estimates that DoD’s production costs (not
including development or operation costs) for implementing its current plans would total $240billion over
the next few decades.
•
Expanding forces to START II limits (3,000 to 3,500warheads) or to START I limits (6,000warheads)
could be accomplished by increasing the number of warheads on each missile (which CBO refers to as the
lower-cost approach) or by increasing the number of delivery vehicles (missiles, submarines, and bombers),
which CBO refers to as the more exible approach, or by some combination of the two.
•
Increasing warhead loadings to reach the START II limits would incur about $100million in onetime costs
for DoD. Increasing the number of delivery vehicles while maintaining current warhead loadings would
increase DoD’s onetime costs by up to $172billion over several decades and annual operating costs by
$3billion to $8billion. (All costs are in scal year 2020dollars.)
•
If DoD expanded forces to START I limits using the lower-cost approach, its onetime costs would rise
by $88billion to $149billion and its annual costs by $4billion to $10billion. Under the more exible
approach, DoD’s onetime costs could increase by $410billion to $439billion and its annual costs by
$24billion to $28billion. Total production costs would be nearly triple what DoD is currently planning to
spend on production over the next few decades.
•
Although some of those strategies would require the production of additional warheads, those estimates do not
include additional costs for the Department of Energy to produce more warheads. e estimates also exclude
costs for DoD to establish new operating bases and training facilities, if necessary, or to expand production
capability for delivery vehicles and the platforms that carry them (to accelerate production if that is desired).
Costs, therefore, would probably be higher—in some cases, considerably so—than CBO estimates.
•
Expanding its forces could take the United States many years. Available warheads could be uploaded relatively
quickly, but additional delivery systems and warheads would probably not be available before the late 2030s or
early 2040s. Most of the additional costs of expanding forces would thus occur a few decades from now.
www.cbo.gov/publication/56475
Contents
Summary 1
What Could Happen If New START Expired? 1
How Did CBO Analyze the Issue? 1
What Did CBO Find? 2
What Costs Were Excluded From is Analysis? 4
Background on the Treaty and Arguments For and Against Its Extension 4
Arguments Against Extension 5
Arguments For Extension 6
Possible U.S. Responses to New START’s Expiration 6
Maintain the Status Quo 7
Expand U.S. Intelligence Capabilities 7
Expand Missile Defenses 8
Expand Conventional Missile Forces 8
Expand Nonstrategic Nuclear Forces 9
Strategic Nuclear Forces and Broad Approaches for Their Expansion 9
Current and Planned Nuclear Forces 10
Expansion by Uploading Additional Warheads 10
Expansion by Fielding Additional Delivery Vehicles 12
Costs of Producing New Nuclear Systems 13
Costs of Purchasing Additional Delivery Vehicles 13
Costs of Producing New Warheads 14
Costs of Expanding Strategic Nuclear Forces to the Limits Under Previous Treaties 15
CBO’s Approach 15
BOX 1. COUNTING RULES USED IN THIS ANALYSIS 16
Costs of Expanding Forces to Moscow Treaty Limits 17
Costs of Expanding Forces to START II Treaty Limits 17
Costs of Expanding Forces to START I Treaty Limits 19
List of Tables and Figures 21
About This Document 22
Notes
Unless this report indicates otherwise, all years referred to are federal scal years,
which run from October1 to September30 and are designated by the calendar year
in which they end.
Numbers in the text and tables may not add up to totals because of rounding.
In this report, “cost” refers to budget authority, the amount that would need to be
appropriated to implement the Administration’s plans. All costs are in scal year
2020dollars.
On the cover (clockwise from upper left): an Ohio class submarine, a B-52bomber, a
Minuteman III intercontinental ballistic missile, and a B-2bomber.
The Potential Costs of Expanding U.S. Strategic
Nuclear Forces If the New START Treaty Expires
Summary
e New Strategic Arms Reduction Treaty (New
START) between the United States and Russia will
expire in February2021unless both parties agree to an
extension, which could last for up to ve years. at
treaty places limits on the number of deployed strategic
nuclear warheads (1,550) and delivery systems (800
missile launchers and bombers, 700 of which may be
deployed at any given time) that each country may eld.
How and when the United States or Russia would
respond to the expiration of New START is unclear. To
help policymakers understand the budgetary implica-
tions of one potential course of action the United States
could take, the Congressional Budget Oce was asked
to examine the potential costs that the Department of
Defense (DoD) might incur if the United States chose
to increase its strategic nuclear forces to levels that are
roughly consistent with the limits under three earlier
arms control treaties.
What Could Happen If New START Expired?
If the New START treaty was allowed to expire, the size
of the nuclear arsenals of the United States and Russia
would be without limits for the rst time in decades.
e transparency and condence-building procedures
included in New START and previous treaties would
cease, in which case both parties would lose the means to
have direct knowledge of their adversary’s capabilities. In
the absence of on-site inspections, data exchanges, and
limits on the encryption of ight text data, uncertainty
about each other’s forces would grow over time.
Many responses to the end of strategic nuclear arms
control would be possible, including some that would
not aect the size of strategic nuclear forces. For exam-
ple, uncertainty about the other party’s forces might lead
the United States to expand its intelligence capabilities
or to hedge against uncertainty about the other party’s
intentions by expanding missile defenses. Conversely, the
United States might choose to emphasize conventional
deterrence by expanding its conventional missile forces
or to increase its capabilities for regional conict by
expanding nonstrategic nuclear forces.
In terms of strategic nuclear forces, many dierent
responses also are possible. Each party might opt to
make no changes to its current plans for nuclear forces
for many years. Or one party might choose to expand its
forces, either to seek an advantage or because, without
the ability to inspect the other’s forces, it was concerned
that the other is building up its arsenal and wants to
hedge against that uncertainty. Or both parties might
choose to expand their forces, perhaps signicantly. e
lack of constraints on ballistic missile defenses could
further complicate that dynamic. (e United States
withdrew from the ABM Treaty, which limited the num-
ber and locations of Russian and U.S. defenses against
long-range missiles, in 2002.)
How Did CBO Analyze the Issue?
CBO was asked to estimate the costs of increasing
deployed U.S. strategic nuclear forces to the levels speci-
ed in three previous arms control treaties: the Moscow
Treaty (1,700 to 2,200warheads), the START II treaty
(3,000 to 3,500warheads), and the START I treaty
(6,000warheads). Although each treaty had a dierent
protocol for counting warheads, for this analysis CBO
used the rules for the Moscow Treaty because they most
closely reect the number of nuclear weapons actually
deployed.
e United States could eld a wide variety of force
structures, each with very dierent costs, to reach
those levels. To illustrate both ends of the distribution
of potential forces and their associated costs, CBO
examined two approaches for expanding forces at each
warhead level.
•
A lower-cost and less exible approach would increase
the number of warheads allocated to each missile and
bomber to, or near to, its maximum (an approach
2 The PoTenTial CosTs of exPanding U.s. sTraTegiC nUClear forCes if The new sTarT TreaTy exPires aUgUsT 2020
known as uploading) and minimize the number of
additional delivery systems purchased, if any.
•
A more exible and higher-cost approach would
purchase enough delivery systems to reach the desired
total numbers of warheads while maintaining (as
nearly as possible) the current number of warheads
allocated to each missile and bomber.
DoD also could choose to eld a force that lies between
those two approaches. To estimate costs, CBO used
methods from its previous work on nuclear forces.
1
1. See Congressional Budget Oce, Approaches for Managing the
Costs of U.S. Nuclear Forces, 2017 to 2046 (October 2017),
www.cbo.gov/publication/53211.
What Did CBO Find?
If the New START treaty expired, the United States
could choose to make no changes to its current plans for
nuclear forces, in which case it would incur no additional
costs. If the United States chose to increase its forces in
response to the expiration of the treaty, modest expan-
sions could be relatively inexpensive and could be done
quickly. Larger expansions could be quite costly, how-
ever, and could take several decades to accomplish (see
Table 1). Accelerating production of additional forces
would probably have only a small eect on that timeline
and could increase costs.
•
Expanding forces to the Moscow Treaty limits would
have no eect on DoD’s costs, because current and
Table 1 .
Approaches for Fielding Nuclear Warheads at Selected Treaty Limits
Additional Costs for DoD
(Billions of 2020 dollars)
Approach Description
Total Number of
SDVs
One-Time
Acquisition Costs
Annual Operation
and Sustainment
Costs
Moscow Treaty
No Change
From Current
Plans
Keep the plans for current-generation and
next-generation forces as they are
As planned 0 0
START II
Lower Cost
(Upload only)
Reach START II levels with currrent-generation or planned next-
generation forces by uploading ICBMs and SLBMs to highest levels
As planned 0.1 0
More Flexible Expand next-generation forces to 3,000 warheads at current SLBM
and ICBM warhead loadings
1,004 to 1,221 114 to 172 3 to 8
START I
Lower Cost Expand next-generation forces to 6,000 warheads by
uploading warheads to high levels; purchase sucient new SDVs
1,043 to 1,359 88 to 149 4 to 10
More Flexible Expand next-generation forces to 6,000 warheads at
current ICBM loadings; purchase sucient new SDVs to
reach limit of 1,600
1,544 to 1,600 410 to 439 24 to 28
Source: Congressional Budget Oce.
Costs are for production of delivery systems only and do not include research and development costs or the Department of Energy’s costs to produce,
sustain, or store more nuclear warheads (if necessary).
The lower-cost approach would increase the number of warheads on delivery systems (known as uploading) and minimize the number of additional
delivery systems; the more flexible approach would purchase additional delivery systems to reach the desired warhead levels, preserving as much as
possible the flexibility provided by today’s smaller number of warheads on each delivery vehicle. Other approaches to expand forces would lie between
those two approaches.
Under the Moscow Treaty, warheads are limited to 1,700 to 2,000, and there are no limits on SDVs (ballistic missiles and bombers). Under START II,
warheads are limited to 3,000 to 3,500, and there are no limits on SDVs. Under START I, warheads are limited to 6,000 and SDVs to 1,600.
DoD = Department of Defense; ICBM = intercontinental ballistic missile; SDV = strategic delivery vehicle; SLBM = submarine-launched ballistic missile;
START = Strategic Arms Reduction Treaty.
3aUgUsT 2020 The PoTenTial CosTs of exPanding U.s. sTraTegiC nUClear forCes if The new sTarT TreaTy exPires
planned next-generation forces are both already at
those limits.
•
Expanding forces to START II limits could be
relatively inexpensive if DoD used a lower-cost
approach that involved uploading warheads only:
about $100million in onetime costs for DoD (with
no additional ongoing operation and sustainment
costs) for both current and next-generation forces,
CBO estimates. If DoD used a more exible
approach that involved purchasing enough delivery
systems to maintain current warhead loading levels,
that expansion would be much more expensive,
eventually totaling $114billion to $172billion in
acquisition costs over several decades and $3billion
to $8billion in additional annual costs after the
expanded forces were in place. e additional costs
of expanding to START II limits under the more
exible approach would lead to total production costs
roughly 50percent higher than currently planned (see
Figure 1).
•
Expanding forces to START I limits would require
even more new delivery systems and warheads.
Under a lower-cost approach that minimized the
number of additional delivery systems, DoD would
incur onetime costs of $88billion to $149billion
over several decades to buy additional delivery
vehicles and $4billion to $10billion in additional
operation and sustainment costs each year, in CBO’s
estimation. Under a more exible approach that
maintained as much as possible the current number
of warheads loaded on missiles and allocated to
bombers by having DoD purchase enough delivery
systems, CBO estimates that DoD would incur
onetime costs eventually totaling $410billion to
$439billion to purchase additional systems as well
as additional annual operation and sustainment costs
(beyond those for planned forces) of $24billion to
$28billion after the expanded forces were in place.
e additional costs of expanding to START I limits
under the more exible approach would lead to
Figure 1 .
Estimated Total DoD Production Costs for Planned Next-Generation Nuclear Forces and
Expanded Nuclear Forces at Dierent Force Levels
Billions of Fiscal Year 2020 Dollars
START II
Level
START I
Level
0 100 200 300 400 500 600 700 800
Lower-Cost
Approach
Other
Approaches
More Flexible
Approach
Planned Forces
and Moscow
Treaty Forces
a
Under the more flexible
approach, the additional
costs of expanding to START
II limits would lead to total
production costs roughly
50percent higher than
those currently planned.
For START I, the costs would
be nearly three times those
currently planned.
Source: Congressional Budget Oce.
DoD = Department of Defense; START = Strategic Arms Reduction Treaty.
Costs are for production of delivery systems only and do not include research and development costs or the Department of Energy’s costs to produce,
sustain, or store more nuclear warheads (if necessary).
The lower-cost approach would increase the number of warheads and minimize the number of additional delivery systems; the more flexible approach
would purchase additional delivery systems to reach the desired number of warheads, preserving as much as possible the flexibility provided by
today’s smaller number of warheads on each delivery vehicle. Other approaches to expand forces would lie between those two approaches.
a. Current and planned next-generation forces are both already at Moscow Treaty limits, so there would be no additional costs.
4 The PoTenTial CosTs of exPanding U.s. sTraTegiC nUClear forCes if The new sTarT TreaTy exPires aUgUsT 2020
production costs nearly three times those currently
planned (see Figure 1).
For comparison, the costs to produce the currently
planned quantities of next-generation delivery systems
is about $240billion, CBO estimates, not including
development costs.
What Costs Were Excluded From This Analysis?
e gures cited in this report do not include the
Department of Energy’s (DOE’s) costs of producing or
maintaining additional warheads. Most information
about the nuclear stockpile is classied, so it is di-
cult to determine whether and how many additional
warheads would be needed and thus what additional
funding would be required. ose costs could be consid-
erable, though, for all but modest increases in forces.
CBO’s estimates also exclude DoD’s costs of establishing
new operating bases and training facilities (if needed)
and DoD’s costs of expanding production capability
for delivery systems (if needed because production
is accelerated). CBO also excluded the costs of other
actions that the United States might take if New START
expired without another agreement in place, including
expanding U.S. intelligence capabilities, strengthening
missile defenses, increasing long-range conventional (that
is, nonnuclear) missile forces, or expanding short-range
nuclear forces.
Background on the Treaty and
Arguments For and Against Its Extension
e New START treaty is the latest in a series of strate-
gic nuclear arms control treaties—following START I,
START II, and the Moscow Treaty—between the United
States and Russia (or the Soviet Union).
2
ose four
treaties, which together span more than 25years of con-
tinuous coverage, placed increasingly stringent limits on
the size (and sometimes the capability) of each country’s
2. e four most recent U.S.–Russian nuclear strategic arms control
agreements are (in chronological order): the Treaty on the
Reduction and Limitation of Strategic Oensive Arms (known
as START I); the START II treaty, which was signed by the U.S.
and Russian presidents but was never fully ratied and never
entered into force; the Strategic Oensive Reductions Treaty (or
the Moscow Treaty); and the Treaty on Measures for the Further
Reduction and Limitation of Strategic Oensive Arms (known
as the New Strategic Arms Reduction Treaty, or New START).
For details on those agreements, see Amy F. Woolf, Paul K. Kerr,
and Mary Beth D. Nikitin, Arms Control and Nonproliferation: A
Catalog of Treaties and Agreements, Report for Congress RL33865
(Congressional Research Service, updated March26, 2020).
strategic nuclear arsenal (see Table 2).
3
e New START
treaty limits each country to 800 total deployed and
nondeployed strategic delivery vehicles (SDVs) and mis-
sile launchers, 700deployed SDVs, and 1,550deployed
warheads. ose limits represent about a 50percent
decrease in “accountable” (counting toward the total)
SDVs and a 75percent decrease in accountable warheads
from the limits in the START I treaty (although the
rules for counting warheads diered markedly between
the two treaties). e New START treaty will expire in
February2021unless both Russia and the United States
agree to extend it for up to ve years.
In addition to placing limits on the size of strategic
nuclear forces, the New START treaty (like the others
before it) provides extensive verication, data exchange,
and condence-building measures that allow each party
insight into the other’s capabilities. In New START,
those measures include the following:
•
Up to 18on-site inspections each year (and the right
to verify the number of warheads on an SDV of the
inspector’s choice);
•
Biannual declarations of the total number of SDVs,
the number of warheads on each type of SDV, and
the bases where they are located;
•
Notication whenever the status of any SDV changes
(if it switches from deployed to not deployed, for
example, or if it is relocated to a dierent base); and
•
A pledge to not interfere with the other party’s
national technical means (which primarily refers to
satellite imagery and electronic signals collection
during testing), including not concealing SDVs from
satellite observation.
Whether the New START treaty should be extended
has been the subject of debate. Administration ocials
have said that the United States would prefer to pursue a
new trilateral treaty that would include both Russia and
China.
4
Statements from Russian ocials have generally
3. Nuclear weapons are referred to as strategic if the delivery system
(ground-launched missile, submarine-launched missile, or
bomber) is capable of delivering them over long ranges, typically
3,000miles or more. Nuclear weapons that are deliverable over
shorter ranges are referred to as nonstrategic, or tactical, weapons.
4. See Department of State, Oce of the Spokesperson, “Brieng
With Senior State Department Ocial on the New START”
(March9, 2020), https://go.usa.gov/xwt94.
5aUgUsT 2020 The PoTenTial CosTs of exPanding U.s. sTraTegiC nUClear forCes if The new sTarT TreaTy exPires
supported the extension of New START.
5
China has
stated that it has “no intention to participate” in trilateral
arms control negotiations.
6
Arguments Against Extension
Opponents of extending the treaty often cite a history
of Russian violations of other treaties as a reason to not
extend this one. Other arguments against extension are
centered on shortcomings of the New START treaty:
5. See Ankit Panda, “Putin: Russia Ready to Extend New START
With U.S. ‘Without Any Preconditions,’” e Diplomat
(December 6, 2019), https://tinyurl.com/ycbpssyn.
6. See Agence France-Presse, “China Says It Has ‘No Intention’ of
Joining Arms Talks With U.S. and Russia,” South China Morning
Post (January 22, 2020), https://tinyurl.com/y7je8o8g.
Opponents contend that even though the treaty may
have met U.S. and allied national security requirements
in 2010, it no longer does because it does not cover
new developments, including growth in the number of
Russian shorter-range nuclear weapons capable of strik-
ing North Atlantic Treaty Organization (NATO) allies
of the United States.
7
(New START places no limits on
nonstrategic nuclear weapons
, of which Russia has sub-
stantially more than the United States.)
In addition, opponents argue that the treaty does not
cover new exotic systems that Russia has developed while
7. See Eric Edelman and Franklin C. Miller, “Russia Is Beeng Up
Its Nuclear Arsenal; Here’s What the U.S. Needs to Do,” Politico
(December31, 2019), https://tinyurl.com/sgej9z6.
Table 2 .
Details of Recent Strategic Arms Control Treaties
New START Moscow (SORT) START II
a
START I
Timeline
Entry Into Force 2011 2003 n.a. 1994
Deadline to Meet Limits 2018 2012 n.a. 2001
Expiration 2021 2011
b
n.a. 2009
Limits on Forces
Number of Strategic Delivery
Vehicles
800 n.a. n.a. 1,600
Number of Deployed Strategic
Delivery Vehicles
700 n.a. n.a. n.a.
Number of Warheads 1,550 1,700 to 2,200 3,000 to 3,500 6,000
Warhead Counting Rules
Description Deployed bombers count as
1 warhead each; deployed
ICBMs and SLBMs count as
the actual number of war-
heads deployed rather than
a fixed maximum value
No counting rules described
in the treaty's text; the
United States informed
Russian negotiators it would
use actual deployed war-
heads on ICBMs and SLBMs
and bomber weapons
deployed on bombers or
stored at bomber bases
Phased out bomber dis-
counts from START I (see
the next panel) but allowed
ICBMs and SLBMs to count
as fewer than the maximum
under some conditions
Warhead count set to the
maximum number tested
on each platform, except
the first 150 bombers that
carry cruise missiles were
discounted to count as 10
warheads each (compared
with 20 maximum on the
B-52); bombers that carry
only bombs count as
1 warhead each
Warheads on Current Forces
as Calculated Using Each
Treaty's Counting Rules
1,467 1,962 2,760 3,920
Source: Congressional Budget Oce, using information from the Department of State, the Nuclear Threat Initiative, and the Arms Control Association.
ICBM = intercontinental ballistic missile; SLBM = submarine-launched ballistic missile; SORT = Strategic Oensive Reductions Treaty; START = Strategic
Arms Reduction Treaty; n.a. = not applicable.
a. The START II treaty was negotiated and signed, but it was never fully ratified and never entered into force. Both sides largely complied with its terms,
however.
b. The Moscow treaty was not scheduled to expire until 2012. However, it was superseded by New START when that treaty went into eect.
6 The PoTenTial CosTs of exPanding U.s. sTraTegiC nUClear forCes if The new sTarT TreaTy exPires aUgUsT 2020
New START has been in force and, given the bilateral
nature of the treaty, places no constraints on China’s
expanding nuclear forces. ose analysts often argue that
there is no rush to extend the treaty and that holding
out on extension could be used as leverage to negotiate
improvements to the existing agreement or perhaps a
new trilateral agreement that includes China.
8
Other
critics argue that Russia uses arms control as a tool for
competition by locking in advantages through the terms
of the treaty.
9
One analysis asserts that New START’s
approach of counting the actual number of deployed
warheads and disregarding the potential for loading
more warheads on SDVs has positioned Russia to be
able to expand its forces much more rapidly than the
United States. at conclusion is based on assertions that
Russia’s intercontinental ballistic missiles (ICBMs) have
the capacity to carry many more warheads than they do
currently and that Russia has the ability to manufacture
thousands of new warheads each year.
10
Arguments For Extension
Proponents of extending the treaty oer counter-
arguments. ey contend that Russia has consistently
complied with the New START treaty (despite violating
some earlier treaties). Proponents also argue that engag-
ing China in arms control talks is a worthwhile goal but
will be dicult and that extending New START would
provide “a necessary foundation from which to pursue
more ambitious arms control talks.”
11
Moreover, extend-
ing New START would provide time for what would
probably be long and extensive negotiations for a mul-
tilateral arms control agreement or for making changes
to New START. For example, including nonstrategic
weapons in a modied New START or a new bilateral
agreement would take time because Russia would proba-
bly ask for limits on U.S. missile defenses in return.
12
8. See Rebecca L. Heinrichs, “Automatically Extending New
START Will Not Increase Stability,” Real Clear Defense
(February28, 2020), https://tinyurl.com/yak99rrq.
9. See omas G. Mahnken, Forging the Tools of 21st Century Great
Power Competition (Center for Strategic and Budgetary Analysis,
2020).
10. See Mark B. Schneider, “Russian Nuclear Force Expansion and
the Failure of Arms Control,” Real Clear Defense (October29,
2019), https://tinyurl.com/y7ldmfa8.
11. See Kingston Reif, Responses to Common Criticisms About
Extending New START, Arms Control Association Issue Brief,
vol.12, no. 1 (February 5, 2020), https://tinyurl.com/ybuhx3fk.
12. See Frank A. Rose, Brookings Institution, “Deterrence,
Modernization, and Alliance Cohesion: e Case for Extending
Additionally, proponents point out that, as a signatory
to the international Non-Proliferation Treaty, the United
States, along with all nations possessing nuclear weapons,
is obligated to pursue reductions in its nuclear arsenal.
13
One analysis that assessed the military implications of
the expiration of New START concluded that the United
States would lose insight into Russian forces that was
provided by on-site inspections; that loss, in turn, would
probably lead to increased costs associated with expand-
ing intelligence capabilities or personnel and would also
probably lead to a costly expansion of planned U.S.
nuclear modernization programs.
14
at analysis argued
that Russia has the ability to upload and produce more
warheads quickly, which would enable that country to
expand its strategic nuclear forces at a faster rate than
the United States could (at least initially). at potential
Russian advantage is a reason to extend New START,
according to proponents, not to let it expire.
Possible U.S. Responses to New START’s
Expiration
e United States might keep its current plans for
nuclear forces unchanged, even if it decides not to renew
New START. According to public reports from shortly
after the New START treaty went into force, DoD
concluded that Russia “would not be able to achieve a
militarily signicant advantageby any plausible expan-
sion of its strategic nuclear forces, even in a cheating or
breakout scenario under the New START Treaty, primar-
ily because of the inherent survivability of the planned
U.S. strategic force structure, particularly the Ohio class
ballistic missile submarines, a number of which are at sea
at any given time.”
15
e United States might conclude
that that assessment is still valid even if New START has
expired.
Whether the United States chose to increase its nuclear
forces might depend on the circumstances. For example,
New START With Russia,” Order From Chaos (blog entry,
January16, 2020), https://tinyurl.com/ycmszay5.
13. See omas Countryman, “Russia, China, Arms Control,
and the Value of New START,” Arms Control Today
(November2019), https://tinyurl.com/yanfmw3n.
14. See Frank G. Klotz, e Military Case for Extending the New
START Agreement (RAND Corporation, February2020),
www.rand.org/pubs/perspectives/PE350.html.
15. See Department of Defense, as cited in Hans Kristensen,
Federation of American Scientists, “DoD: Strategic
Stability Not reatened Even by Greater Russian Nuclear
Forces,” Strategic Security Blog (October10, 2012)
https://fas.org/blogs/security/2012/10/strategicstability/.
7aUgUsT 2020 The PoTenTial CosTs of exPanding U.s. sTraTegiC nUClear forCes if The new sTarT TreaTy exPires
if Russia uploaded warheads onto its ICBMs but did not
increase the number of ICBMs, the United States might
opt not to act, if the current U.S. force was deemed ade-
quate to cover the assigned targets. If Russia’s uploading
of warheads passed a certain point, however, a deci-
sion might be made that too large a Russian numerical
advantage would cause foreign policy problems. In that
case, even if the United States still felt there was no mil-
itary reason to expand its force, it might do so to avoid
problems that could aect crisis management, unnerve
U.S. allies, or embolden Russian leaders to threaten use
of nuclear weapons. In another case, if neither Russia nor
the United States increased their forces after the treaty’s
expiration but China did, either Moscow or Washington
(or both) might decide that additional nuclear forces
were needed.
A U.S. response, should one occur, could happen soon
after the treaty expired or in later years. If the treaty was
not extended, the resulting lack of transparency and
on-site inspections over time could lead to increasing
U.S. uncertainty about Russian forces and could create
pressure to act. As a hedge against that uncertainty, U.S.
planners might decide to expand strategic nuclear forces.
Such an expansion could occur in a number of ways.
CBO was asked to analyze a range of potential costs that
might be incurred if forces were expanded to levels con-
sistent with the limits established under three previous
arms control treaties (see Table 2 on page 5).
In addition to expanding strategic nuclear forces (or
instead of doing so), the United States could take other
actions if the treaty was not extended: It could expand its
intelligence capabilities, for instance, or it could expand
its missile defenses, conventional forces, or nonstrategic
nuclear forces (that is, nuclear weapons that are delivered
by shorter-range systems, like certain tactical aircraft).
ose actions could be spurred by a real or perceived
expansion of Russian forces, concern about uncertainty
of the state of Russian nuclear forces in the absence of
verication, or some other stimulus. Taking any of those
actions (or, as is more likely to occur, taking a combi-
nation of two or more of them, possibly in addition to
expanding strategic nuclear forces) could impose costs on
the United States. CBO has not estimated those costs,
however, given the signicant uncertainty about what
actions might be taken and to what extent.
Maintain the Status Quo
e United States could decide that its forces, as cur-
rently planned, are appropriate and sucient for the
geopolitical environment, even in the absence of trea-
ties that constrain strategic nuclear forces and permit
inspections and other transparency measures. Current
plans already call for the development of new technolo-
gies in several areas (some of which are described below)
to respond to advances in the capabilities of potential
adversaries.
Not expanding U.S. strategic nuclear forces in response
to an expansion of Russian strategic nuclear forces would
represent a change in U.S. strategy. Historically, the
United States has generally pursued a deterrence strategy
that features elements of both punishment and denial to
varying degrees. According to that strategy, the best way
to avoid nuclear war is to deny the adversary any plau-
sible notion of victory, however it denes victory, at any
level of nuclear conict, from limited strikes through an
all-out nuclear exchange.
16
at strategy could change
for a number of reasons, however, including a decision to
fund other defense priorities instead.
Hewing to the status quo would not increase DoD’s costs
beyond those it expects to incur for currently planned
programs.
Expand U.S. Intelligence Capabilities
e United States elds a variety of satellites, both
classied and unclassied, to collect intelligence about
adversaries through high-resolution imagery, infrared
detection of missile launches, interception of electro-
magnetic communication, and other methods. Without
insight into Russian strategic forces from on-site inspec-
tions and other transparency measures provided by a
treaty, the United States would probably need to rely
more heavily on satellite intelligence; moreover, it might
feel the need to increase the number of satellites in orbit
or purchase more commercial satellite imagery (or both)
and bolster its capabilities to analyze intelligence data.
17
ose approaches are not without risk, however. e
New START treaty, like the treaties that preceded it, pro-
hibits interference with the other party’s national techni-
cal means (a catchall term for intelligence and national
security satellites and other means to verify treaty com-
pliance). If that prohibition expired, U.S. satellites would
16. For more details, see Congressional Budget Oce, Approaches for
Managing the Costs of U.S. Nuclear Forces, 2017 to 2046 (October
2017), pp.24–25, www.cbo.gov/publication/53211.
17. For a more detailed discussion of the consequences of the lack of
transparency into Russian forces, see Vince Manzo, Nuclear Arms
Control Without a Treaty? Risks and Options After New START,
Deterrence and Arms Control Paper no.1 (CNA Corporation,
March2019), pp.38–49, www.cna.org/research/NAC.
8 The PoTenTial CosTs of exPanding U.s. sTraTegiC nUClear forCes if The new sTarT TreaTy exPires aUgUsT 2020
be at risk of interference ranging from performance
degradation (through jamming or other techniques) to
destruction from a direct attack.
18
If the United States decided to replace or augment its
intelligence systems, the costs could be sizable. High-
capability satellites can be expensive—for example,
producing the fth and sixth geostationary satellites
in the Space-Based Infrared Satellite-High system, an
unclassied missile launch detection constellation, cost
an average of about $1.1billion each (in 2020dollars).
Because it is unclear what steps, if any, the United States
would take to compensate for the loss of monitoring and
transparency measures that would have been provided
under New START, CBO did not estimate those costs.
Expand Missile Defenses
e United States could strengthen its defenses against
long-range ballistic missiles if it concluded that the risk
of a nuclear attack from Russia had increased or that
stronger defenses would be prudent in the face of uncer-
tainty about the state of Russian nuclear forces. Such an
expansion in missile defenses would constitute a signi-
cant policy change, however. Previous statements of U.S.
missile defense policy, including the 2019Missile Defense
Review, have held that missile defenses of the homeland
were intended to counter long-range missile attacks from
rogue states and that nuclear deterrence was intended to
address the nuclear threat from Russia and China.
Currently, U.S. missile defense comes primarily from
the Ground-Based Midcourse Defense (GMD) system,
which comprises silo-based long-range interceptor mis-
siles in Alaska and California, supported by an array of
radars around the world. at system is complemented
by Aegis Ballistic Missile Defense interceptors based both
on ships and at ground sites; a test is slated for later this
year to determine the ecacy of Aegis against ICBMs.
e 2019 Missile Defense Review stated that GMD could
be expanded by building new silos at the Alaska base if
“emerging threat conditions” suggested they were needed.
19
18. See eresa Hitchens, “End of New START Could Risk U.S.
Sats: Aerospace Corp.,” Breaking Defense (January15, 2020),
https://tinyurl.com/yassuhrk.
19. See Department of Defense, Missile Defense Review (January
2019), p. XVI, https://go.usa.gov/xwtmx (PDF, 26.6 MB).
Building 40new silos at the Alaska GMD base and
purchasing interceptors for them would cost about
$5 billion, CBO estimates. at amount is very uncer-
tain, though, because the GMD program is in the early
stages of a complete redesign.
20
e United States also
could choose to expand or accelerate the development of
other missile defense systems, including those designed
to counter new hypersonic weapons (described in the
next section), which would result in additional costs.
Expand Conventional Missile Forces
e United States could choose to increase its conven-
tional (that is, nonnuclear) capabilities to strengthen
deterrence, if an expansion was deemed necessary to
respond to an unconstrained Russian strategic nuclear
force. One way to do that would be to accelerate or
otherwise expand development programs for hypersonic
weapons or conventional intermediate-range ballistic
missiles (IRBMs). Both of those types of weapons are
already under development for conventional missions
to counter Russia’s and China’s antiaccess strategies.
21
ose weapons also could be designed to perform some
missions that in the past might have required nuclear
weapons, like striking high-value or hardened targets at
long range on short notice.
Hypersonic weapons have three salient characteristics, all
of which give them advantages over other weapons and
make them dicult to defend against:
•
ey can travel at least ve times the speed of sound
(or Mach 5, which is equivalent to about 3,800miles
per hour or 1.7kilometers, or km, per second) for at
least part of their trajectory;
•
ey spend a signicant fraction of their trajectory
(the midcourse phase) ying through the upper
atmosphere and use the atmosphere to provide lift;
and
20. See Congressional Budget Oce, Assessing the Cost of
the Recommendations of the 2019Missile Defense Review
(forthcoming).
21. Antiaccess strategies are actions that would impede the
deployment of U.S. forces into the combat theater, limit the
locations from which those forces could eectively operate, or
force them to operate from locations farther from the locus of
conict than they would normally prefer. See Roger Cli and
others, Entering the Dragon’s Lair: Chinese Antiaccess Strategies and
eir Implications for the United States (RAND, 2007).
9aUgUsT 2020 The PoTenTial CosTs of exPanding U.s. sTraTegiC nUClear forCes if The new sTarT TreaTy exPires
•
ey have the ability to maneuver to avoid enemy
defenses in the midcourse phase.
Several U.S. programs are seeking to develop hypersonic
weapons, including hypersonic glide weapons (which
are launched with a rocket booster and then use aero-
dynamic lift to maneuver and to extend their range).
At least one program is developing a hypersonic cruise
missile (which is launched with a rocket booster to gain
enough speed to enable it to use an exotic engine called
a scramjet to reach hypersonic speeds). Some of those
programs have begun ight-testing their prototypes.
e United States also could choose to accelerate
or expand its development and elding of ground-
launched IRBMs now that it is no longer constrained
by the Intermediate-Range Nuclear Forces treaty. at
treaty barred the United States and Russia from pos-
sessing ground-launched cruise or ballistic missiles with
ranges between 500 km and 5,500 km (or 300miles to
3,400miles). Citing an ongoing Russian violation of
the treaty, the United States recently withdrew from it.
Currently, at least one program is working on developing
a conventionally armed IRBM.
Programs to develop hypersonic and IRBM weapons are
in the early stages, so their development and production
costs are not yet known. For that reason, CBO did not
estimate those costs.
Expand Nonstrategic Nuclear Forces
e United States currently elds only one type of
nonstrategic nuclear weapon, the B61bomb, which
is carried by F-15E tactical aircraft as well as NATO
allies’ aircraft.
22
According to one report, about 150 of
those bombs are based in Europe in support of NATO,
and some are stored in the United States.
23
Unclassied
sources estimate that Russia, by comparison, maintains a
substantially larger stockpile of about 1,800nonstrategic
22. ere are several versions of the B61 bomb. Some are carried
by tactical aircraft for nonstrategic missions, whereas others are
carried by B-2 bombers for strategic missions. e Department of
Energy’s B61-12 life-extension program, which is currently in the
design phase, will combine the current types into a single version
that can perform both strategic and nonstrategic missions.
23. ose bombs also can be carried by NATO partners’
aircraft. See Hans M. Kristensen and Matt Korda, “United
States Nuclear Forces, 2020,” Bulletin of the Atomic
Scientists (January2020), https://thebulletin.org/2020/01/
united-states-nuclear-forces-2020/.
warheads that can be delivered by several dierent
vehicles.
24
Citing Russia’s advantage in the number and types
of nonstrategic nuclear weapons it elds, the most
recent Nuclear Posture Review (NPR), released in
January2018, called for putting the United States on a
path to expand its nonstrategic nuclear forces by devel-
oping and elding a new nuclear-armed, sea-launched
cruise missile (SLCM). DoD is analyzing alternatives to
determine the concept for the SLCM.
In 2019, CBO estimated that the cost of elding a
SLCM would be about $9 billion (in current dollars).
CBO assumed that the design of the SLCM would draw
heavily from the Long-Range Stando (LRSO) weapon,
a nuclear-armed, air-launched cruise missile now in
development.
25
(CBO’s estimate did not include the
costs to integrate the SLCMs onto the ships selected to
carry them or associated costs like nuclear-specic train-
ing, weapon storage, or security.)
If the United States felt that conditions warranted addi-
tional expansion of nonstrategic nuclear forces, it could
develop nuclear warheads for hypersonic missiles or
IRBMs (discussed in the previous section) or add nuclear
capability to one of the Navy’s tactical aircraft. ose
approaches would incur additional costs; operation costs
for training, weapon storage, and security could be sub-
stantial, particularly if nuclear weapons were deployed on
platforms that do not currently carry them.
Strategic Nuclear Forces and
Broad Approaches for Their Expansion
e Department of Defense operates a strategic nuclear
force that complies with the limits specied in the New
START treaty (up to 1,550warheads and 800deliv-
ery vehicles and missile launchers, 700 of which can
be deployed). ose forces are aging, so DoD has
started replacing them—a process that will continue
over the next few decades. If the United States decided
to expand its strategic nuclear forces, DoD could do
so in two ways: by uploading warheads on currently
24. See Hans M. Kristensen and Matt Korda, “Russian Nuclear
Forces, 2020,” Bulletin of the Atomic Scientists (March2020),
https://thebulletin.org/2020/03/russian-nuclear-forces-2020/.
25. See Congressional Budget Oce, Projected Costs of U.S. Nuclear
Forces, 2019 to 2028 (January2019), p. 4, www.cbo.gov/
publication/54914.
10 The PoTenTial CosTs of exPanding U.s. sTraTegiC nUClear forCes if The new sTarT TreaTy exPires aUgUsT 2020
elded delivery systems or by elding additional deliv-
ery systems. Any substantial expansion of U.S. forces in
response to a real or perceived Russian buildup would
probably include a combination of the two.
To develop the approaches used in this analysis, which
would increase nuclear forces to the limits set in previous
treaties, CBO considered force structures comprising
either currently deployed systems or next-generation
systems that are being developed to replace the current-
generation systems. Reconstituting nuclear forces as
they had been deployed (or had planned to be deployed)
when the previous treaties were in force is not possi-
ble. Many of the systems that were in service then have
been out of production for decades and have since been
retired, have had their inventory substantially reduced, or
have been converted to serve only nonnuclear roles.
Current and Planned Nuclear Forces
For many years, U.S. strategic nuclear forces have been
made up of three components: intercontinental ballistic
missiles, ballistic missile submarines (SSBNs) carry-
ing long-range submarine-launched ballistic missiles
(SLBMs), and long-range bombers carrying nuclear
bombs or nuclear-armed cruise missiles; together,
those forces are commonly referred to as the triad. e
Department of Defense currently elds these systems:
•
Ohio class SSBNs that are congured to carry
20D5SLBMs,
•
Silo-based Minuteman III ICBMs,
•
B-52H bombers that carry Air-Launched Cruise
Missiles (ALCMs), and
•
B-2A bombers that carry B61 and B83bombs. (For
quantities and other details for all of those systems,
see Table 3, top panel).
Nearly all of those systems are nearing the end of their
operational life, and many have undergone one or more
life-extension programs (LEPs). Over the past decade,
DoD has been designing replacements for those systems,
most of which are slated to enter production over the
next ve years or so. e next-generation systems will
comprise the following:
•
Columbia class SSBNs carrying 16 existingD5
SLBMs and, eventually, newly constructed SLBMs
using an updated design of the D5missile,
•
Ground-Based Strategic Deterrent (GBSD) ICBMs
in refurbished Minuteman III silos,
•
B-52H bombers with new engines and other
refurbishments carrying LRSO cruise missiles, and
•
New B-21bombers, which will be capable of carrying
both B61nuclear bombs and LRSOs. (For details, see
Table 3, bottom panel).
26
At planned rates of production, those new systems will
not be fully in place until the early 2040s.
As congured, current- and next-generation forces
comply with New START’s limits on delivery systems
and deployed warheads, according to the denitions and
counting rules laid out in that treaty. e rules with the
greatest impact are those that aect how warheads are
counted: Deployed ICBMs and SLBMs count as the
actual number of warheads they carry, whereas deployed
bombers count for only a single warhead each (regard-
less of how many warheads they carry). To meet the
1,550-warhead limit, therefore, current forces carry an
average of 4.2warheads on each deployed SLBM (individ-
ual SLBMs might carry any number up to the maximum
load of 8), deployed Minuteman III ICBMs carry 1war-
head each (by U.S. policy, out of a maximum of 3 for that
missile), and deployed bombers count as 1warhead each
(see the description in Table 2 on page 5).
27
Expansion by Uploading Additional Warheads
Current versions of SLBMs and ICBMs are capable of
carrying more warheads than they typically do under
New START. Similarly, the next generation of deliv-
ery vehicles would also have the capacity to carry more
warheads than they most likely would be allowed to do
under New START rules if the treaty remained in force
(see Table 3).
26. For more details on those modernization programs, see
Congressional Budget Oce, Approaches for Managing the
Costs of U.S. Nuclear Forces, 2017 to 2046 (October 2017),
www.cbo.gov/publication/53211.
27. e counting rule for bombers was chosen to balance the
facts that bombers are capable of carrying nuclear weapons
but that neither the United States nor Russia keeps bombers
loaded with those weapons on a day-to-day basis. See Senate
Committee on Foreign Relations, Treaty With Russia on Measures
for Further Reduction and Limitation of Strategic Oensive Arms
(e New START Treaty), Exec. Report 111-6 (October 1,
2010), www.congress.gov/111/crpt/erpt6/CRPT-111erpt6.pdf
(701 MB).
11aUgUsT 2020 The PoTenTial CosTs of exPanding U.s. sTraTegiC nUClear forCes if The new sTarT TreaTy exPires
If enough warheads of the correct types were available,
the current generation of forces could carry up to about
4,600, and the next generation of forces (when fully
elded) could carry up to about 4,400, CBO estimates.
(ose numbers are theoretical maximums; they include
full weapon loads on all bombers and incorporate the
idealized assumption that all delivery systems would be
in good repair and available.)
28
at approach would be
roughly consistent with the counting rules of the START
I treaty, which did not distinguish between deployed and
nondeployed delivery vehicles and which attributed to
28. For this analysis, CBO’s estimates of next-generation forces
incorporate the assumption that the B-21bomber could carry
up to eight nuclear weapons, half the number that the B-2A
can carry. e actual number and types of nuclear weapons
the B-21will carry have not been publicly disclosed. For a
public analysis of the potential capabilities of the B-21, see
David Cenciotti and Tom Denerly, “Let’s Have a Look at
the New B-21‘Raider’ Stealth Bomber Renderings the Air
Force Has Just Released,” e Aviationist (January 31, 2020),
https://tinyurl.com/ya6kvudz.
each delivery vehicle the maximum number of warheads
used in any test of that system (except for bombers,
which counted as fewer warheads than they were capable
of carrying).
In all likelihood, however, the United States would not
be able to eld that many warheads in practice, primarily
because they would not be available. According to the
most recent unclassied data released by the Department
of Defense, the United States’ nuclear stockpile totaled
3,822warheads as of 2017.
29
Another estimate, from
an oft-cited public analysis of U.S. nuclear forces, puts
the number of strategic warheads at 3,570, compris-
ing 800ICBM warheads, 1,920SLBM warheads, and
850bomber warheads (with an additional 230nonstra-
tegic warheads), as well as about 2,000warheads that
29. See Department of Defense, “U.S. Nuclear Weapons Claims and
Responses” (April2019), https://go.usa.gov/xwtvc (PDF, 2.82
MB).
Table 3 .
U.S. Nuclear Forces, as Currently Planned
How Deployed Warheads
Would Count Under
Treaty Counting Rules
Triad
Component
Delivery Systems
Under Current Plans
Warheads If
Delivery Systems
Loaded to
Maximum Capacity New START Moscow Comments
Current Generation of Forces
SSBNs 14 Ohio class submarines with
280 D5 SLBMs (20 per submarine)
2,240 1,008 1,008 8 warheads maximum per SLBM; currently
deployed average about 4.2 per SLBM
ICBMs 450 silos with 400 MMIII missiles 1,200 400 400 3 warheads maximum per ICBM; actual
deployed ICBMs have 1 each by policy
Bombers 43 B-52Hs and 20 B-2As 1,180 56 524 20 warheads maximum per B-52;
16 warheads per B-2
Total 791
4,620 1,464 1,932
Next Generation of Forces
SSBNs 12 Columbia class submarines with
192 D5 SLBMs (16 per submarine)
1,536 739 739 8 warheads maximum per SLBM;
deployed average 4.2 per SLBM
ICBMs 450 silos with 400 GBSD missiles 1,200 400 400 3 warheads maximum per ICBM;
1 warhead per deployed ICBM
Bombers 43 B-52Hs and 100 B-21s 1,660 128 740 20 warheads maximum per B-52;
8 warheads per B-21
Total 783
4,396 1,267 1,879
Source: Congressional Budget Oce.
GBSD = Ground-Based Strategic Deterrent; ICBM = intercontinental ballistic missile; MMIII = Minuteman III; SLBM = submarine-launched ballistic missile;
SSBN = ballistic missile submarine; START = Strategic Arms Reduction Treaty.
12 The PoTenTial CosTs of exPanding U.s. sTraTegiC nUClear forCes if The new sTarT TreaTy exPires aUgUsT 2020
have been retired and are awaiting dismantlement.
30
ose estimates, if accurate, suggest that it would not be
possible to load any of the three components of the triad
to their full potential capacity or to eld any congura-
tion of nuclear forces with more than about 3,800war-
heads, without either returning retired warheads to active
service or producing new warheads, either of which
could incur substantial costs and delays. CBO has not
estimated those costs in this analysis because it is not
clear to what extent those actions would be required.
At times, the number of available delivery systems
would probably be smaller than CBO estimates, too. As
current-generation delivery systems were retired and were
replaced by newly produced next-generation systems, a
period of reduced inventory would probably occur, par-
ticularly for SSBNs; if the program stays on schedule, the
United States is expected to have 10of them for several
years (down from 14 now) before reaching the planned
goal of 12. Maintaining current-generation systems at
high levels of availability as they near the end of their
operational life also might prove dicult.
31
In addition to the practical reasons for elding ICBMs
and SLBMs at less than their full warhead loading, that
conguration might make sense for operational and
policy reasons. Many nuclear analysts have argued that
placing more than one warhead on silo-based ICBMs
(which have xed and widely known locations) is stra-
tegically destabilizing because those missiles present an
inviting target: By attacking such an ICBM, an adversary
could destroy multiple warheads at once and gain an
advantage. e 2010Nuclear Posture Review established
a U.S. policy to eld only single-warhead ICBMs, and
the 2018NPR continued that policy. Operationally,
increasing the weight that a missile has to carry reduces
30. at estimate combines weapons in the active and inactive
stockpiles. Weapons in the inactive stockpile have had certain
limited-lifetime components removed to reduce maintenance
requirements. If needed, those weapons could be returned to
active status; the time required to do so would depend on the
condition of each weapon, whether it was up to date on life
extensions and other modications that active weapons of its type
received, and the availability of limited-lifetime components,
particularly tritium. For an unclassied analysis of the size and
composition of the U.S. stockpile, see Hans M. Kristensen and
Matt Korda, “United States Nuclear Forces, 2020,” Bulletin of the
Atomic Scientists (January2020), https://thebulletin.org/2020/01/
united-states-nuclear-forces-2020/.
31. See Rachel S. Cohen, “Report: ICBMs to Fall Short of Mission
Needs in 2026,” Air Force Magazine (March30, 2020),
https://tinyurl.com/ycrfymmt.
its maximum range, so carrying the full load of warheads
on an ICBM might require changing its assigned targets.
Similarly, loading SLBMs with more warheads could
force SSBNs to operate in areas closer to their targets
(as they did during the Cold War). at conguration
would require more time for the submarines to transit to
and from their operating areas at the beginning and end
of their deployments and would reduce planners’ exibil-
ity in choosing operating areas.
Expansion by Fielding Additional Delivery Vehicles
e United States could expand its nuclear forces
by elding additional strategic delivery vehicles—an
approach that would provide limited options for growth
with the current generation of delivery vehicles but
more options for the next generation of vehicles. ose
additional purchases of next-generation systems would
probably not be available for decades, however, unless
production capacity for DoD’s delivery systems and
DOE’s nuclear production facilities was expanded, which
would require a signicant investment.
Current-Generation Delivery Vehicles. Potentially, the
number of deployed current-generation delivery vehi-
cles could be increased from the current 700 to as many
as about 880 (the number that the United States had
before New START) without producing new systems,
probably within several years of the decision to do so.
Expanding the number of current-generation delivery
vehicles beyond 880, however, is unlikely to occur. All of
those systems have been in service for many years, and
replacement systems are in development. For those rea-
sons, CBO did not consider the possibility of producing
additional current-generation systems.
To meet the limits for deployed delivery vehicles under
the New START treaty, the United States had to reduce
its inventory of each type of vehicle. To do so, it took
three actions: disabling four SLBM launch tubes on each
Ohio class SSBN (decreasing the number of opera-
tional tubes from 24 to 20per submarine), removing
50Minuteman III ICBMs from their silos, and con-
verting about 30B-52H bombers to conventional-only
missions.
Increasing the number of deployed delivery vehicles
would mean reversing at least one of those actions. e
most straightforward would be increasing the number
of deployed ICBMs by returning up to 50missiles to
their silos, because the United States elected to keep
the 50emptied silos in an operational status to serve
13aUgUsT 2020 The PoTenTial CosTs of exPanding U.s. sTraTegiC nUClear forCes if The new sTarT TreaTy exPires
as backups during the GBSD program’s planned silo
refurbishment. e total stock of Minuteman III missiles
is limited, though, so placing additional missiles in silos
might adversely aect their testing and reliability pro-
gram.
32
Before the missiles were removed, the Air Force
estimated that the costs of removing them from their
silos and storing them would be $20million (in cur-
rent dollars) over the 2014–2018period. Returning the
missiles to their silos might incur similar costs, although
some of those silos would probably be left empty to
facilitate refurbishment.
Some analysts have argued that it may be possible to
reverse the changes made to SSBN tubes or B-52H
bombers as a means to expand the number of current-
generation delivery systems. ose actions—if possible—
could probably be accomplished more quickly and at a
lower cost than purchasing new next-generation delivery
vehicles.
Next-Generation Delivery Vehicles. Expanding the
number of next-generation delivery systems could be
accomplished by increasing the number produced.
Production of each of those systems is expected to run
for many years. If the additional units were produced at
the end of the planned production run for each system,
the full complement of additional systems would proba-
bly not be available before the mid-2040s.
If DoD funded additional production facilities, then it
might be possible to get those extra systems deployed
sooner by accelerating their production. Construction
costs could be substantial, though, particularly for
SSBNs. And even if production started sooner than
planned, it would still take many years to produce the
desired quantity of delivery vehicles.
Costs of Producing New Nuclear Systems
e main contributors to the costs of producing new
nuclear systems are the costs to purchase additional
delivery vehicles and the costs to produce new warheads.
CBO used analyses from its previous reports to estimate
the marginal costs of producing additional delivery
systems and warheads. But CBO’s estimates of the costs
to expand nuclear forces to treaty levels do not include
DOE’s costs to produce additional warheads, because
information about the current inventory of weapons is
classied so it is not clear how many warheads would be
required.
32. Ibid.
e estimates also do not include other potential sources
of substantial costs: the cost to sustain new warheads for
the delivery systems to carry, should that be necessary;
the cost to add production capacity for delivery systems
or for warheads, should that be necessary; and the cost to
establish and operate new bases for the delivery systems,
should those be required.
Costs of Purchasing Additional Delivery Vehicles
To estimate the costs of producing additional delivery
systems—submarines, missiles, and bombers—CBO
grouped those systems into sets (see Table 4). For exam-
ple, the estimated cost for an SSBN includes the cost of
the submarine plus the cost of 18SLBMs, comprising
the 16that a single SSBN carries plus 2spares. Using
that general approach, CBO estimates that purchas-
ing one outtted Columbia class SSBN would cost
$8.5billion, one launch control center’s worth of silos
and ICBMs would cost $1.0billion, and one B-21with
LRSO cruise missiles would cost about $0.5billion (all
in 2020dollars).
Unlike ICBMs and SSBNs, which are exclusively nuclear
systems, bombers perform both nuclear and non-
nuclear missions. CBO’s estimates include the full cost
of additional B-21 bombers because they are needed to
reach the desired levels of nuclear forces. ose aircraft
also would be available to perform nonnuclear missions,
however, and thus would increase U.S. conventional
capabilities as well.
ose estimates draw heavily on previously published
CBO analyses. In particular, CBO’s approach for esti-
mating the production costs for delivery systems in this
report is the same one it used in its 2017 report on the
30-year costs of nuclear forces.
33
Production costs were
estimated using a model in which additional production
would occur at the end of the planned production run,
when the unit cost of produced units is typically at its
lowest. ose production runs are currently scheduled to
be completed in the late 2030s or early 2040s. If addi-
tional delivery systems were desired earlier, it might be
necessary to construct additional production facilities,
but CBO did not estimate the costs to do so.
33. Costs in this report have been updated to 2020 dollars. For
details on the methodology CBO used, see Congressional Budget
Oce, Approaches for Managing the Costs of U.S. Nuclear Forces,
2017 to 2046 (October 2017), Appendix A, www.cbo.gov/
publication/53211.
14 The PoTenTial CosTs of exPanding U.s. sTraTegiC nUClear forCes if The new sTarT TreaTy exPires aUgUsT 2020
CBO’s estimates of marginal operation and sustainment
costs are based on the actual costs of analogous systems.
34
ey incorporate the assumption that, as the size of the
eet changes, half of all operation and sustainment costs
would be xed, and half would vary linearly with the size
of the force. If the size of the eet doubled, for instance,
the xed half of operation and sustainment costs would
stay the same, whereas the variable half of those costs
would double, resulting in operation and sustainment
costs for the double-sized eet that were 150percent of
the costs of the original eet.
Costs of Producing New Warheads
Expanding the number of warheads in the stockpile
could add to costs in two ways: e additional warheads
would need to be produced, and larger production facili-
ties might need to be built to support a larger stockpile.
Although CBO could not estimate the total costs for the
Department of Energy to produce enough new warheads
to reach the limits under the various treaties, it was able
to roughly estimate the average cost of producing each
additional warhead by gauging the average marginal cost
to produce a new warhead of a type that is already in
the stockpile. (at estimate does not include the costs
to develop the design and procedures for producing
34. Sustainment means providing incremental upgrades to a system
over time, often by adding components that are easier to
maintain or that add capability.
the warhead.) DOE is in the process of performing life
extensions on essentially all of the types of warheads in
the stockpile. Drawing on analysis done for a previous
report, CBO estimates that the average production cost
per warhead for those LEPs would be about $9million
to $12million, assuming that there was a one-to-one
replacement of warheads in the existing active stockpile.
One variable that would aect the costs of producing
new warheads is whether enough plutonium pits of the
appropriate type would be available.
35
Life-extension
programs generally reuse a plutonium pit from an
existing warhead, but there may not be enough exist-
ing pits to support a substantial increase in the size of
the stockpile. DOE is in the planning stages for a new
plutonium pit facility, but completion would be years
away. Based on an analysis of DOE’s information about
operating costs for that facility when it reaches full
production capacity of 50pits per year, CBO estimates
that the marginal cost of producing a pit would be about
$6million. Combining that cost with the other warhead
production costs yields a rough marginal cost estimate
of $15million to $20million per warhead. us, if
3,000new warheads were required to expand U.S. forces
to the START I limit of 6,000, for example, the total
35. A pit is a hollow shell of ssile material, such as plutonium, at
the core of a modern nuclear weapon. Detonation of the weapon
begins with the implosion of the pit. Each type of nuclear
weapon generally uses a custom-designed pit.
Table 4 .
CBO’s Estimates of DoD’s Marginal Costs of Purchasing Additional Next-Generation Delivery Vehicles
Triad Component Items Purchased
Maximum
Warhead
Capacity
Added
Marginal One-Time
Acquisition Cost
(Billions of
2020 dollars)
Additional Annual
Operation and
Sustainment Costs
(Millions of
2020 dollars)
Department of
Energy's Additional
Costs to Produce,
Sustain, and Store
New Warheads Comments
SSBNs 1 Columbia class SSBN
and 18 D5 SLBMs
128 8.5 180 Not estimated Includes 2 spare SLBMs
ICBMs 10 silos and
11 GBSD ICBMs
30 1.0 20 Not estimated ICBMs are grouped as 10
per launch control center;
includes 1 spare ICBM
Bombers 1 B-21 and 10 LRSO
cruise missiles
8 0.5 40 Not estimated Includes 2 spare LRSOs
Source: Congressional Budget Oce, using information from the Department of Defense.
Marginal cost is the cost added by producing one additional unit of a product or service.
CBO did not estimate DoD’s costs of new bases or new facilities for training and maintenance (if needed).
GBSD = Ground-Based Strategic Deterrent; ICBM = intercontinental ballistic missile; LRSO = Long-Range Stando weapon; SLBM = submarine-launched
ballistic missile; SSBN = strategic ballistic missile submarine.
15aUgUsT 2020 The PoTenTial CosTs of exPanding U.s. sTraTegiC nUClear forCes if The new sTarT TreaTy exPires
cost for new warheads would be about $45billion to
$60billion. at estimate is highly uncertain, though,
primarily because it is not clear how well LEP costs serve
as an analogue for the costs of producing a new warhead.
If the number of warheads in the stockpile was
expanded, DOE might need to make some changes to its
weapons complex beyond those it already has planned.
Many of its production facilities are more than 40years
old. Over the past several years, DOE has developed
a plan to rebuild much of the infrastructure used to
produce the components that make up nuclear war-
heads: the plutonium pits; strategic materials, such as
tritium; and other nonnuclear components, including
radiation-hardened electronics and the conventional
explosives used to begin the nuclear chain reaction in the
warhead.
In its scal year 2021budget submission, DOE esti-
mated that it would need $15.5billion (in current
dollars) to modernize its production facilities over the
2021–2025period, and additional funding for that
eort is slated to run through the mid-2040s. If DOE’s
planned facilities are sized to support a future stockpile
that is the same size as the current one, though, and later
the decision is made to expand the stockpile substan-
tially, those planned facilities might need to be expanded
as well. DOE also would have to increase its capacity to
maintain a larger stockpile. ose changes, if necessary,
would incur additional costs, possibly substantial, partic-
ularly if the United States returned its nuclear forces to
START I levels.
Costs of Expanding Strategic Nuclear Forces
to the Limits Under Previous Treaties
Because it is unclear how the United States might expand
its strategic nuclear forces if New START expired, CBO
looked at a range of possible outcomes using the limits
under the Moscow Treaty, the START II treaty, and the
START I treaty. Each treaty had a unique set of rules for
counting the number of warheads and delivery vehicles.
To make the possible outcomes under the various treaties
easier to compare, CBO used a single set of counting
rules—those from the Moscow Treaty, which come the
closest to counting the actual number of deployed war-
heads (see Box 1).
CBO’s Approach
e United States could expand its nuclear forces by
uploading warheads on missiles, elding additional
delivery systems, or doing both. Because myriad com-
binations are possible, CBO estimated costs for the full
range of possible combinations but focused on two gen-
eral approaches—one at each end of the spectrum—to
show the range of potential costs:
•
A lower-cost and less exible approach under which
the United States would expand its nuclear forces
primarily by uploading warheads on missiles and
increasing the number of warheads allocated to each
bomber to, or nearly to, the maximum level while
elding as few additional delivery systems as possible;
and
•
A more exible and higher-cost approach under
which the United States would expand its nuclear
forces primarily by elding additional delivery
systems while maintaining, to the extent possible,
the current levels of warhead loading on missiles and
warheads allocated to bombers.
e lower-cost approach would be less expensive gener-
ally because it would lead to the purchase of fewer new
delivery systems. e more exible approach would be
more expensive generally, but it would allow expanded
forces to operate in a manner similar to that of current
forces by maintaining current warhead loadings.
Increasing the number of warheads on missiles reduces
their maximum range. Under the lower-cost approach,
fully loaded ICBMs might not be able to reach all of
their currently assigned targets, and SSBNs might have
to change their operating areas to reach all of their
current targets. Having fewer warheads on delivery
vehicles—as the more exible approach would do—
might provide more capability to execute limited nuclear
strikes, yielding more exibility in managing nuclear
escalation.
Criteria at CBO Considered. In constructing
potential force structures, CBO considered only those
in which warheads would be distributed among the
components of the triad in proportions that were
roughly similar to those of current forces and planned
next-generation forces (when possible). Historically,
each component of the triad has been thought to make
a unique contribution to deterrence, so elding an
expanded force with a structure close to that of current
16 The PoTenTial CosTs of exPanding U.s. sTraTegiC nUClear forCes if The new sTarT TreaTy exPires aUgUsT 2020
or planned forces would maintain a similar mix of those
deterrence features.
36
Applying the Moscow Treaty’s counting rules to
current-generation forces means that about half of
accountable warheads are carried on SLBMs, and ICBMs
and bombers each account for about one-quarter of war-
heads. Similarly, for next-generation forces as currently
36. In brief, SSBNs provide survivable nuclear weapons and thus
guarantee the ability to execute a retaliatory second strike if
an adversary strikes the United States; ICBMs provide rapid
response and a large number of targets that raise the threshold
for a potential adversary’s disarming rst strike; and bombers
provide exibility by allowing leaders to ramp up operations
quickly (to signal intent to an adversary) and by being able to be
recalled after launch if circumstances change. For more details,
see Congressional Budget Oce, Approaches for Managing the
Costs of Nuclear Forces, 2017 to 2046 (October 2017), Chapter 3,
www.cbo.gov/publication/53211.
planned, SLBMs and bombers would each account for
about 40percent of warheads under those counting
rules, and ICBMs would account for about 20percent.
CBO considered force structures that t roughly within
the range between those two cases.
In addition, CBO considered only expanded forces
that would use the same delivery systems as currently
planned—that is, Columbia class SSBNs, GBSD silo-
based ICBMs, B-52H bombers, and B-21bombers. e
United States could consider developing other delivery
systems, though, particularly if forces were expanded
substantially. For example, DoD’s original analysis of
alternatives that led to creation of the GBSD program
also considered a mobile ICBM concept.
37
Development
37. See Jason Sherman, “Trump Administration Wants to Retain
Option for Road-Mobile GBSD Variant,” Inside Defense (July18,
2019), https://tinyurl.com/y85fq6zz.
Box 1.
Counting Rules Used in This Analysis
To estimate the potential costs of expanding strategic nuclear
forces to the levels defined in the Moscow, START II, and
START I arms control treaties, the Congressional Budget Oce
needed to select an appropriate method for counting the
number of warheads for a given set of nuclear forces. Each
treaty has a set of negotiated counting rules to calculate the
number of “accountable” warheads of each party to determine
if they comply with the treaty’s limits.
1
Generally, those rules
were customized to address concerns about the makeup of the
forces at the time; for example, when the START I treaty was
negotiated in 1991, the United States was concerned about
Russia fielding large intercontinental ballistic missiles (ICBMs)
capable of carrying many warheads, so the rules count each
missile as having the maximum number of warheads that a
missile can carry rather than the (smaller) number with which
it might typically be outfitted. Because of those idiosyncrasies,
the numbers of accountable warheads can dier markedly
depending on which counting rules are applied to a given force
(see Table 2 on page 5).
For consistency in comparing illustrative forces, CBO selected
a single set of counting rules—those used for the Moscow
Treaty in 2002—to determine the number of accountable war-
heads for each of the forces. Specifically, CBO used the rules
1. Accountable warheads are those that count toward the maximum overall
limits provided for in the treaty. They are not necessarily the same as the
actual number of deployed warheads.
described in the transmittal documents submitting the treaty
to the Congress: the actual number of warheads on deployed
ICBMs and submarine-launched ballistic missiles (SLBMs), plus
the number of warheads either loaded on deployed bombers
or stored at active bomber bases.
2
That formulation corresponds roughly to the number of war-
heads that the United States could bring to bear within a few
weeks during a crisis and thus has a meaningful operational
basis, particularly in a world without limits on nuclear forces.
On the basis of its analysis of U.S. annual reports on treaty
implementation and unclassified analyses of the makeup
of U.S. strategic forces, CBO estimates that the number of
accountable bomber warheads when the Moscow Treaty was
in force was approximately half of the maximum warhead
capacity for the deployed bomber force. In CBO’s application
of the Moscow Treaty’s counting rules, deployed ICBMs include
silos that have ICBMs in them, and deployed SLBMs include all
missiles carried by submarines that are not being overhauled.
CBO’s application of those rules also incorporates the assump-
tion that 90percent of delivery systems are deployed.
2. See “Message From The President of the United States Transmitting
the Treaty Between the United States of America and the
Russian Federation on Strategic Oensive Reduction, Signed
at Moscow on May24, 2002,” Senate Treaty Document 107-8,
www.congress.gov/107/cdoc/tdoc8/CDOC-107tdoc8.pdf (522KB).
17aUgUsT 2020 The PoTenTial CosTs of exPanding U.s. sTraTegiC nUClear forCes if The new sTarT TreaTy exPires
of a new delivery system would incur additional costs,
but it could lead to lower overall costs than those of the
other force structures considered in this report, and the
United States could choose to pursue it for operational
or nancial reasons. However, CBO did not consider the
development of any new delivery systems in estimating
the costs of expanded forces.
CBO’s Estimates of Costs. To show the range of DoD’s
potential costs under each treaty, CBO estimated the
costs of the full range of possible combinations of forces
that added up to the treaty’s limit on warheads and still
met the criteria described above. ose combinations
were based on varying the number of components:
SSBNs and the warheads carried by each SLBM on those
submarines, ICBMs and the warheads carried by each
of those missiles, and B-21bombers. (e number of
B-52bombers was not varied.)
Unlike ICBMs and SSBNs, which are exclusively nuclear
systems, bombers perform both nuclear and nonnuclear
missions. CBO’s estimates include the full cost of addi-
tional B-21 bombers because they would be needed to
reach the desired levels of nuclear forces. ose aircraft
also would be available to perform nonnuclear missions,
however, and thus would increase U.S. conventional
capabilities as well.
For treaties that have a range for the maximum number
of warheads they allow, CBO assessed the cost of forces
at the lower end of that limit—1,700 for the Moscow
Treaty and 3,000 for the START II treaty. CBO did
not consider decreasing any components of the triad; in
other words, it excluded congurations that would eld
fewer than the planned number of delivery systems of
any type or that would load missile warheads at an aver-
age of less than 4per SLBM or 1per ICBM.
e resulting set of possible congurations provided a
range of potential costs. Force congurations that cor-
respond to what CBO has referred to as the lower-cost
approach (which favors uploading warheads over pur-
chasing any new delivery systems) generally have costs
at the low end of the distribution for a given treaty;
congurations that correspond to the more exible
approach (which prioritizes purchasing enough delivery
systems to require little or no uploading of warheads on
missiles beyond current levels) generally have costs at the
high end of the distribution. ose two approaches are
meant to illustrate what force structures and costs would
look like at the ends of the cost distribution. Many other
approaches and congurations are possible.
Regardless of the approach chosen, actual costs for the
forces in each range would probably exceed CBO’s esti-
mates because they exclude two types of costs.
•
First, they exclude any costs incurred by DOE for
additional warheads. If production of new warheads
was necessary to reach the levels for a certain treaty,
the process could take longer, and DOE could incur
substantial costs.
•
Second, they exclude any costs for DoD to build
additional weapons storage and maintenance facilities
at bases or to establish operations at any additional
bases, if those became necessary.
CBO has not estimated those costs because it is not clear
whether and to what extent new warheads or new facil-
ities might be needed. e size of those excluded costs
probably increases with the extent of the expansion of
DoD’s forces, so greater expansion means more costs that
are not included in CBO’s estimates.
Costs of Expanding Forces to Moscow Treaty Limits
Under the Moscow Treaty’s counting rules, both the
current generation of forces and the planned next
generation of forces would meet its limit of 1,700 to
2,200 warheads with no changes and, thus, would not
incur any additional costs (see Table 3 on page 11).
Although that limit is higher than currently allowed
under New START, more warheads are counted toward
that limit under the Moscow Treaty’s counting rules,
which fully account for the weapons that have been
assigned to bombers. Under New START’s counting
rules, by contrast, each bomber accounts for only one
warhead.
Costs of Expanding Forces to START II Treaty Limits
CBO examined two approaches to constructing forces
that would carry 3,000 to 3,500 warheads, the number
allowed under the START II treaty.
38
e lower-cost
approach would upload warheads on existing and
next-generation forces, and the more exible approach
would purchase enough additional next-generation
delivery vehicles to reach START II limits using warhead
38. START II’s limits on warheads were to be implemented in two
phases. is analysis uses the more restrictive limits from the
second phase.
18 The PoTenTial CosTs of exPanding U.s. sTraTegiC nUClear forCes if The new sTarT TreaTy exPires aUgUsT 2020
loadings as they are today (to preserve the exibility
provided by that conguration).
Lower-Cost Approach. e United States could reach
the START II warhead limit for the current and next
generation of forces by increasing warhead loadings to
near their maximum capacity on ICBMs and SLBMs
and increasing the number of warheads allocated to
bombers to near their maximum capacity (see Table 5,
top panel). If enough warheads of the appropriate types
were available, increasing warhead loadings to that extent
could probably be accomplished within a few years,
CBO estimates, and would cost about $100million
(based on the cost that DoD has reported for removing
warheads from delivery systems to comply with the limit
under the New START treaty).
Increasing the number of warheads to 3,000 or more
would put the total number close to the current stockpile
of 3,800 active and inactive warheads. Probably only
a few force structures, if any, could be elded solely by
uploading warheads without producing any new war-
heads. And producing new warheads would extend the
time required to reach the START II warhead levels and
would boost costs (which CBO did not estimate).
Table 5 .
Examples of Nuclear Force Structures That Could Be Implemented to Reach START II Warhead Limits
DoD's Additional Costs
(Billions of 2020 dollars)
Triad
Component Delivery Systems
Warheads
at Maximum
Capacity
Deployed
Warheads
(CBO's
estimate)
One-Time
Acquisition
Costs
Annual
Operation and
Sustainment
Costs
Department of Energy’s
Additional Costs to
Produce, Sustain, and
Store New Warheads Comments
Lower-Cost and Less Flexible Approach
SSBNs 12 Columbia class
submarines with
192 D5 SLBMs
1,536 1,408 0 0 Not estimated No additional SSBNs; 8 war-
heads per SLBM, on average
ICBMs 450 silos with
405 GBSD missiles
1,350 810 0 0 Not estimated No additional ICBMs; 2 war-
heads per ICBM, on average
Bombers 43 B-52Hs and
100 B-21s
1,660 782 0 0 Not estimated No additional bombers;
warheads at about half-full
bomber capacity
Total 785
4,546 3,000 0
a
0
More Flexible and Higher-Cost Approach
SSBNs 19 Columbia class
submarines with
304 D5 SLBMs
2,432 1,169 60 1 Not estimated 7 additional SSBNs with
SLBMs; 4.3 warheads per
SLBM, on average
ICBMs 550 silos with
495 GBSD missiles
1,650 495 10 0 Not estimated 100 additional ICBMs;
1 warhead per ICBM
Bombers 43 B-52Hs and
266 B-21s
2,988 1,336 91 7 Not estimated 166 additional B-21s with
LRSOs; warheads at about
half-full bomber capacity
Total 1,163
7,070 3,000 160
b
8
b
Source: Congressional Budget Oce.
The approaches described in this table are two illustrative examples of the many force structures that CBO included in its cost range for expanding U.S.
forces to START II treaty levels. The costs are estimated using the marginal cost factors from Table 4. The lower-cost approach to increasing warheads
to START II limits (3,000 to 3,500) would increase the number of warheads on each missile; the more flexible approach would increase the number of
delivery vehicles.
DoD = Department of Defense; GBSD = Ground-Based Strategic Deterrent; ICBM = intercontinental ballistic missile; LRSO = Long-Range Stando
weapon; SLBM = submarine-launched ballistic missile; SSBN = strategic ballistic missile submarine; START = Strategic Arms Reduction Treaty.
a. Under the lower-cost approach, warheads could be uploaded only at a onetime additional cost of about $100 million. That approach might require
the production of new warheads, but CBO did not estimate the costs to do so.
b. The more flexible approach could incur costs for new warhead production, sustainment and infrastructure, production facilities for new delivery
systems, and new bases and training facilities; CBO did not estimate the costs for any of those items, however.
19aUgUsT 2020 The PoTenTial CosTs of exPanding U.s. sTraTegiC nUClear forCes if The new sTarT TreaTy exPires
More Flexible Approach. e United States could expand
to START II warhead levels for next-generation forces
by purchasing additional delivery systems. Warhead
loading levels would stay close to their current values
(4.2per SLBM, on average, and 1per ICBM), and
warheads allocated to the bomber eet would remain at
about half of the maximum capacity. at more exible
approach would incur additional onetime acquisition
costs of between $114billion and $172billion over
several decades and additional operation and sustain-
ment costs of between $3billion and $8billion a year,
CBO estimates. ose costs would depend on the mix
of additional delivery systems purchased to preserve the
current relative distribution of warheads among the triad’s
components.
As an example, one potential conguration of forces
would require DoD to purchase 7additional Columbia
class SSBNs and associated missiles, 100additional
GBSD ICBMs and associated infrastructure, and
166additional B-21bombers with cruise missiles (see
Table 5 on page 18, bottom panel).
39
To eld and
maintain such a force, DoD would incur onetime
acquisition costs of $160billion and operating and sus-
tainment costs of $8billion a year, CBO estimates. Any
additional costs for DOE would elevate those totals.
e more exible approach would probably require the
production of new warheads, which would increase costs.
CBO did not estimate those additional costs.
Costs of Expanding Forces to START I Treaty Limits
CBO used the same two approaches to illustrate the
range of possible forces under START I, which limits the
number of warheads to a total of 6,000 and the number
of delivery systems to 1,600.
40
e lower-cost approach
would emphasize uploading forces and would require
the purchase of as few additional systems as possible. e
more exible approach would emphasize warhead load-
ings that were roughly similar to those of current forces.
39. e addition of 100 ICBMs comprises adding 100 silos and 110
missiles. CBO’s estimate of the number of deployed warheads
incorporates the assumption thatmissiles would be deployed
in90 percent of thosesilos(that is, they are loaded into a silo)
at any given time,which isconsistent with the current fraction
of ICBMs deployed by DoD. e remaining missiles would be
added to the Air Force’s inventory and would be available for
deployment if that was desired.
40. CBO did not apply the sublimits that the treaty created for how
the warheads would be distributed among the components of the
triad, because the treaty is no longer in eect.
Because the 6,000-warhead limit would exceed the
maximum capacity of both current- and next-generation
forces, reaching it would require the purchase of addi-
tional delivery systems—a prospect that would be feasi-
ble only for next-generation forces.
Lower-Cost Approach. To minimize the number of
additional delivery systems needed under the lower-cost
approach, ICBMs and SLBMs could be uploaded to the
greatest extent possible, and the bomber eet could be
sized to match maximum capacity to warheads allocated
to the eet. If missiles were at their full loading (8war-
heads per SLBM and 3 warheads per ICBM), reaching
6,000deployed warheads would cost DoD $88billion to
$149billion in additional onetime acquisition costs and
$4 billion to $10billion a year in additional operation
and sustainment costs. e costs would depend on the
makeup of the additional delivery systems purchased,
although any conguration would need to maintain
roughly the same relative distribution of warheads
among the components of the triad.
One potential conguration of forces would comprise
3additional Columbia class SSBNs with missiles,
150 additional GBSD ICBMs, and 153additional
B-21bombers with cruise missiles. at setup would
cost DoD an additional $124billion in acquisition costs
and $7billion annually in additional operation and
sustainment costs (see Table 6, top panel).
41
e lower-cost approach would probably require the
production of new warheads, which could substantially
increase costs. CBO did not estimate those additional
costs.
More Flexible Approach. It is not possible to reach
6,000warheads while fully preserving the levels of war-
head loading in the current force and remaining below
the START I limit of 1,600delivery systems. To remain
below the limit on delivery vehicles, CBO considered
force congurations that would load a single warhead
on all ICBMs (maintaining current U.S. policy) and
load SLBMs to near their maximum value. ose force
congurations would not maintain the current relative
41. e addition of 150 ICBMs comprises adding 150 silos and 165
missiles. CBO’s estimate of the number of deployed warheads
incorporates the assumption thatmissiles would be deployed
in90 percent of thosesilos(that is, they are loaded into a silo)
at any given time,which isconsistent with the current fraction
of ICBMs deployed by DoD. e remaining missiles would be
added to the Air Force’s inventory and would be available for
deployment if that was desired.
20 The PoTenTial CosTs of exPanding U.s. sTraTegiC nUClear forCes if The new sTarT TreaTy exPires aUgUsT 2020
distribution of warheads among the components of the
triad—the ICBM component would carry a smaller
fraction of warheads than it does currently. Under
those conditions, DoD would incur $410 billion to
$439billion in additional onetime acquisition costs and
$24billion to $28billion in additional annual operation
and sustainment costs, CBO estimates. e range of
costs reects the makeup of additional delivery systems
purchased.
One potential conguration would add 12Columbia
class SSBNs with missiles and 586B-21bombers with
cruise missiles to the force but would not change the
number of GBSD ICBMs. Such a force would cost DoD
$423billion in additional onetime acquisition costs and
$26billion in additional operation and sustainment
costs each year, in CBO’s estimation (see Table 6, bottom
panel).
e more exible approach would probably require the
production of new warheads, which could substantially
increase costs. CBO did not estimate those additional costs.
Table 6 .
Examples of Nuclear Force Structures That Could Be Implemented to Reach START I Warhead Limits
DoD's Additional Costs
(Billions of 2020 dollars)
Triad
Component Delivery Systems
Warheads
at Maximum
Capacity
Deployed
Warheads
(CBO's
estimate)
One-Time
Acquisition
Costs
Annual
Operation and
Sustainment
Costs
Department of Energy’s
Additional Costs to
Produce, Sustain, and
Store New Warheads Comments
Lower-Cost and Less Flexible Approach
SSBNs 15 Columbia class
submarines with
240 D5 SLBMs
1,920 1,792 26 1 Not estimated 3 additional SSBNs with
SLBMs; 8 warheads per
SLBM, on average
ICBMs 600 silos with
540 GBSD missiles
1,800 1,620 14 0 Not estimated 150 additional ICBMs; 3 war-
heads per ICBM, on average
Bombers 43 B-52Hs and
253 B-21s
2,884 2,576 84 6 Not estimated 153 additional B-21s with
LRSOs; warheads at full
bomber capacity
Total 1,059
6,604 5,988 124 7
More Flexible and Higher-Cost Approach
SSBNs 24 Columbia class
submarines with
384 D5 SLBMs
3,072 2,746 102 2 Not estimated 12 additional SSBNs with
SLBMs; 7.8 warheads per
SLBM, on average
ICBMs 450 silos with
405 GBSD missiles
1,350 405 0 0 Not estimated No additional ICBMs;
1 warhead per ICBM
Bombers 43 B-52Hs and
686 B-21s
6,348 2,850 321 24 Not estimated 586 additional B-21s with
LRSOs; warheads at half-full
bomber capacity
Total 1,563
10,770 6,001 423 26
Source: Congressional Budget Oce.
The approaches described in this table are two illustrative examples of the many force structures that CBO included in its cost range for expanding U.S.
forces to START I treaty levels. The costs are estimated using the marginal cost factors from Table 4. The lower-cost approach to increasing warheads
to START I’s limit of 6,000 would increase the number of warheads on each missile and purchase the minimum number of delivery vehicles necessary
to reach the limit; the more flexible approach would maintain as much as possible the current number of warheads loaded on missiles and allocated to
bombers by purchasing enough delivery systems.
Both the lower-cost and more flexible approaches could incur costs for new warhead production, sustainment and infrastructure, production facilities
for new delivery systems, and new bases and training facilities; CBO did not estimate the costs for any of those items, however.
DoD = Department of Defense; GBSD = Ground-Based Strategic Deterrent; ICBM = intercontinental ballistic missile; LRSO = Long-Range Stando
weapon; SLBM = submarine-launched ballistic missile; SSBN = strategic ballistic missile submarine; START = Strategic Arms Reduction Treaty.
Tables
1. Approaches for Fielding Nuclear Warheads at Selected Treaty Limits 2
2. Details of Recent Strategic Arms Control Treaties 5
3. U.S. Nuclear Forces, as Currently Planned 11
4. CBO’s Estimates of DoD’s Marginal Costs of Purchasing Additional
Next-Generation Delivery Vehicles 14
5. Examples of Nuclear Force Structures at Could Be Implemented to
Reach START II Warhead Limits 18
6. Examples of Nuclear Force Structures at Could Be Implemented to
Reach START I Warhead Limits 20
Figure
1. Estimated Total DoD Production Costs for Planned Next-Generation
Nuclear Forces and Expanded Nuclear Forces at Dierent Force Levels 3
List of Tables and Figures
About This Document
is Congressional Budget Oce report was prepared at the request of the Chairman of the
House Armed Services Committee and the Ranking Member of the Senate Foreign Relations
Committee. In keeping with CBO’s mandate to provide objective, impartial analysis, the report
makes no recommendations.
Michael Bennett prepared the report with assistance from Joshua Wolfram, a visiting fellow
at CBO from the Air Force, and with guidance from David Mosher and Edward G. Keating.
Raymond J. Hall assisted in the research. John Kerman fact-checked the report.
Alissa Ardito Ashcroft of CBO provided helpful comments, as did Franklin C. Miller of the
Scowcroft Group, Kingston Reif of the Arms Control Association, and Frank Rose of the
Brookings Institution. (e assistance of external reviewers implies no responsibility for the nal
product, which rests solely with CBO.)
Mark Doms and Robert Sunshine reviewed the report. Christine Bogusz was the editor, and
Robert Rebach was the graphics editor and cover illustrator. An electronic version is available on
CBO’s website (www.cbo.gov/publication/56475).
CBO continually seeks feedback to make its work as useful as possible. Please send any comments
to [email protected]v.
Phillip L. Swagel
Director
August 2020
