Nuclear-Armed Sea-Launched Cruise Missile (SLCM-N)
link to page 1 
Updated July 19, 2024
Nuclear-Armed Sea-Launched Cruise Missile (SLCM-N)
Congress and the executive branch have debated the merits
2020. At the same time, the Navy conducted an Analysis of
of a new nuclear-armed sea-launched cruise missile
Alternatives on the SLCM-N.
(SLCM-N) since the weapon was first proposed by the
Trump Administration in 2018. The Biden Administration
In its FY2022 budget request, the Biden Administration
sought $5.2 million for Department of Defense (DOD)
proposed cancelling the SLCM-N program following its
2022 Nuclear Posture Review (NPR), a periodic assessment
research and development work on the SLCM-N. It also
requested $10 million for the National Nuclear Security
of U.S. nuclear policy. Congress has provided continued
funding for the SLCM-N and its warhead; the FY2024
Administration (NNSA) to study adapting the W80-4
nuclear warhead, intended for the Long-Range Standoff
National Defense Authorization Act (NDAA) requires the
executive branch to ensure SLCM-N initial operational
Weapon (LRSO) air-launched cruise missile, for delivery
carried by the SLCM-N. The Administration also stated that
capability (IOC). Since the FY2024 NDAA, the
Administration has taken steps to begin SLCM-N program
it would review the program in the 2022 NPR.
implementation.
The Biden Administration proposed cancelling the SLCM-
Background
N in the 2022 NPR, arguing that the missile was “no longer
necessary” because of the W76-2 SLBM warhead’s
The U.S. Navy first deployed a nuclear-armed sea-launched
“deterrence contribution.” The Navy’s FY2023 budget
cruise missile in the mid-1980s, when it placed the TLAM-
request eliminated funding for the SLCM-N, stating that the
N—a nuclear-armed version of the Tomahawk land-attack
missile was “cost prohibitive and the acquisition schedule
cruise missile—on surface ships and attack submarines.
would have delivered capability late to need.”
With a range of 2,500 kilometers (about 1,550 miles), the
missiles were not included in the limits in U.S.-Soviet arms
Current Status
control agreements.
The Biden Administration did not include the SLCM-N in
In 1991, at the end of the Cold War, President George H.W.
its FY2023, FY2024, or FY2025 budget requests. The
Bush announced that the United States would withdraw all
Administration’s policy statements on the FY2023 and
land-based tactical nuclear weapons (those that could travel
FY2024 NDAAs asserted that continuing the SLCM-N
less than 300 miles) from overseas bases and all sea-based
program “would divert resources and focus from higher
tactical nuclear weapons from surface ships, submarines,
modernization priorities.” Despite the Administration’s
and naval aircraft. The Navy withdrew the TLAM-N
objections, Congress has provided continued funding for
missiles by mid-1992 and eliminated the nuclear mission
the missile and the associated warhead (see Table 1).
for U.S. surface ships, but retained the option to return the
Table 1. Funding for SLCM-N ($ in millions)
TLAM-N to attack submarines. Some observers
characterized this redeployment ability as demonstrating the
Authorizations and
credibility of U.S. defense commitments to allies in Asia.
Appropriations
FY2023 FY2024
In 2010, the Obama Administration recommended that the
Authorized for SLCM-N
25.0
190.0
Navy retire the TLAM-N missiles. The 2010 NPR stated
that “this system serves a redu
Appropriated for SLCM-N
25.0
130.0
ndant purpose,” as it was one
of several weapons the United States could deploy in
Authorized for SLCM-N warhead
20.0
70.0
support of U.S. allies. The Navy completed the retirement
Appropriated for SLCM-N warhead
20.0
70.0
of these missiles in 2013.
Source: P.L. 117-263; P.L. 118-31; P.L. 117-328; P.L. 118-47; P.L.
The Trump Administration reversed this decision, arguing
118-42.
in the 2018 NPR that a nuclear-armed sea-launched cruise
missile (now known as SLCM-N) would provide the United
Section 1640 of the FY2024 NDAA (P.L. 118-31 of
States with a “non-strategic regional presence” that would
December 22, 2023) directs DOD to establish within 90
address the “need for flexible and low-yield options.”
days a “major defense acquisition program” for the SLCM-
SLCM-N was one of two systems that the 2018 NPR
N under the Undersecretary of Defense for Acquisition and
characterized as “modest supplements” that would
Sustainment (USD A&S), initiate a program to alter the
“strengthen deterrence of regional adversaries” and assure
W80-4 warhead for delivery via SLCM-N, and “ensure”
U.S. allies. The other 2018 NPR-recommended system was
that the system achieves IOC no later than September 30,
a low-yield version of the W76 nuclear warhead (known as
2034. Section 1640 also mandates recurring DOD and
the W76-2) for the Trident D5 long-range submarine-
NNSA briefings on SLCM-N program progress and a report
launched ballistic missile (SLBM). The 2018 NPR stated
due in June 2024 on the “actions required to effectively
that the W76-2 was an option for the “near-term,” while
deploy … [SLCM-N] from a Virginia class submarine and
SLCM-N would be an option implemented over “the longer
such other platforms as the Secretary [of the Navy]
term.” DOD announced the deployment of the W76-2 in
determines appropriate,” as well as potential platform
https://crsreports.congress.gov
Nuclear-Armed Sea-Launched Cruise Missile (SLCM-N)
changes, modifications to port facilities, implications for
visible generation” could provide the President with
manning, and associated costs.
additional signaling and response options in a crisis. In
April 2022 testimony, General Mark Milley, then-Chairman
USD A&S William LaPlante testified in April 2024 that in
of the Joint Chiefs of Staff, also expressed support for the
March 2024 he had directed the “Navy to establish a
SLCM-N, arguing that the President “deserves to have
[SLCM-N] program office and to begin the analysis phase.”
multiple options.” The 2023 final consensus report of the
He also stated that the Nuclear Weapons Council, a joint
Congressional Commission on the Strategic Posture of the
DOD-NNSA coordination group, is “leading a review of
United States did not explicitly endorse the SLCM-N, but
options to execute the SLCM-N program in a manner that
called for a prompt system that is “forward deployed or
balances cost, deterrence value, and risk to the [nuclear
deployable”; “survivable against preemptive attack without
modernization] program of record and the Joint Force.”
force generation day-to-day”; possesses “a range of
Finally, he advocated balancing “SLCM-N programmatic
explosive yield options, including low yield”; and is able to
manning with on-going Navy and NNSA programs”
penetrate adversary integrated air and missile defenses.
because they “draw from a limited pool of experienced
Observers have debated whether a nuclear posture that
government personnel and the same nuclear weapons
includes low-yield capabilities like the SLCM-N and the
industrial base and production enterprise.”
W76-2 and demonstrates a willingness to use nuclear
Vice Admiral Johnny Wolfe, Director of the Navy’s
weapons improves deterrence or increases the risk of
Strategic Plans and Programs, testified in April 2024 that
nuclear war. (See CRS In Focus IF11143, A Low-Yield,
funding appropriated for the SLCM-N in FY2023 “enabled
Submarine-Launched Nuclear Warhead: Overview of the
initial development of a Concept of Operations” and other
Expert Debate.)
activities to prepare for the first of three milestones in
DOD’s acquisition process. Wolfe stated in a May 2024
Arms Control
hearing that the Navy had asked Congress for “flexibility”
Policymakers have debated the potential role of SLCM-N in
to assess various options “that will give us that [SLCM-N]
arms control. The 2018 NPR linked the missile to U.S.
capability with minimum impact” on other Navy and
concerns about a new missile that Russia has deployed in
NNSA modernization priorities.
violation of the 1987 Intermediate-Range Nuclear Forces
(INF) Treaty. Although the United States withdrew from
NNSA Administrator Jill Hruby testified in April 2024 that
the treaty in 2018, the 2018 NPR stated that SLCM-N could
NNSA had established a program office that has been
provide a treaty-compliant U.S. response to Russia’s
working with the Navy and also examining the W80-4 and
violation and incentivize Russia to engage in arms control
“potentially, other warheads that will be least disruptive” to
negotiations concerning nonstrategic nuclear weapons. In
NNSA’s warhead programs. She stated in May 2024
contrast, the 2022 NPR argued that there is “uncertainty
testimony that NNSA’s FY2025 unfunded priorities list
regarding whether SLCM-N on its own would provide
includes $70 million in funding for the SLCM-N warhead.
leverage” in such negotiations. Russia has rejected
negotiations concerning its nonstrategic nuclear weapons,
Issues in the SLCM-N Debate
citing these capabilities as necessary to offset to U.S. and
NATO conventional superiority.
Deterrence Credibility and Flexibility of Options
A key issue in the SLCM-N debate is whether adding the
Operational Tradeoffs and Costs
missile to U.S. nuclear forces is necessary to credibly deter
The Biden Administration argued in a July 2023 policy
limited nuclear use by adversaries and assure allies in
statement that “deploying SLCM-N on Navy attack
Europe and the Asia-Pacific that the United States would
submarines or surface combatants would reduce capacity
protect them from nuclear coercion. The Biden
for conventional strike munitions, create additional burdens
Administration has stated that the United States has the
on naval training, maintenance, and operations, and could
ability in its “current and planned capabilities for deterring
create additional risks to the Navy’s ability to operate in
an adversary’s limited nuclear use through conventional
key regions.” In May 2024 testimony, Navy Secretary
and nuclear armaments,” including the W76-2 SLBM and
Carlos Del Toro expressed concerns about the tactical and
air-delivered weapons such as the “Air-launched Cruise
operational tradeoffs and costs of SLCM-N for the Navy.
Missile, its successor… [the LRSO], and F-35A dual-
capable aircraft that can be equipped with B61-12 nuclear
The 2022 NPR also cited the SLCM-N’s “estimated cost”
gravity bombs.”
as a tradeoff. The Navy stated in 2022 that SLCM-N
cancellation would save $199.2 million in FY2023 and $2.1
SLCM-N proponents have argued that SLCM-N’s attributes
billion over the next five years. Secretary of Defense Lloyd
are different from low-yield capabilities delivered by other
Austin III testified in April 2022 that “the marginal
means. They say that aircraft that deliver weapons would
capability that [the SLCM-N] provides is far outweighed by
need to either be “generated” (fueled, weapons-loaded, and
the cost.” A July 2023 Congressional Budget Office (CBO)
flown) from the United States, which takes time, or else
report estimated the costs of the SLCM-N and its warhead
placed in regional bases, where they could be vulnerable to
at $10 billion from 2023-2032 “if the program began in
adversary strikes. SLCM-N proponents also argue that
2024.” This amount, the CBO noted, does not include
deploying the missile on surface vessels or attack
production costs beyond 2032, or costs for system
submarines provides advantages, such as greater
integration, storage, or operations.
availability and regional presence, over deploying the W76-
2 SLBM on ballistic missile submarines.
SLCM-N supporters argue that the deterrence and
assurance benefits of SLCM-N outweigh these operational
STRATCOM Commander General Anthony Cotton
tradeoffs and costs.
reportedly wrote in 2023 that “a low-yield, non-ballistic
nuclear capability to deter, assure and respond without
This In Focus was originally authored by Amy F. Woolf,
Specialist in Nuclear Weapons Policy.
https://crsreports.congress.gov
Nuclear-Armed Sea-Launched Cruise Missile (SLCM-N)
IF12084
Anya L. Fink, Analyst in U.S. Defense Policy
Disclaimer
This document was prepared by the Congressional Research Service (CRS). CRS serves as nonpartisan shared staff to
congressional committees and Members of Congress. It operates solely at the behest of and under the direction of Congress.
Information in a CRS Report should not be relied upon for purposes other than public understanding of information that has
been provided by CRS to Members of Congress in connection with CRS’s institutional role. CRS Reports, as a work of the
United States Government, are not subject to copyright protection in the United States. Any CRS Report may be
reproduced and distributed in its entirety without permission from CRS. However, as a CRS Report may include
copyrighted images or material from a third party, you may need to obtain the permission of the copyright holder if you
wish to copy or otherwise use copyrighted material.
https://crsreports.congress.gov | IF12084 · VERSION 6 · UPDATED
Updated July 19, 2024
Nuclear-Armed Sea-Launched Cruise Missile (SLCM-N)
Congress and the executive branch have debated the merits
2020. At the same time, the Navy conducted an Analysis of
of a new nuclear-armed sea-launched cruise missile
Alternatives on the SLCM-N.
(SLCM-N) since the weapon was first proposed by the
Trump Administration in 2018. The Biden Administration
In its FY2022 budget request, the Biden Administration
sought $5.2 million for Department of Defense (DOD)
proposed cancelling the SLCM-N program following its
2022 Nuclear Posture Review (NPR), a periodic assessment
research and development work on the SLCM-N. It also
requested $10 million for the National Nuclear Security
of U.S. nuclear policy. Congress has provided continued
funding for the SLCM-N and its warhead; the FY2024
Administration (NNSA) to study adapting the W80-4
nuclear warhead, intended for the Long-Range Standoff
National Defense Authorization Act (NDAA) requires the
executive branch to ensure SLCM-N initial operational
Weapon (LRSO) air-launched cruise missile, for delivery
carried by the SLCM-N. The Administration also stated that
capability (IOC). Since the FY2024 NDAA, the
Administration has taken steps to begin SLCM-N program
it would review the program in the 2022 NPR.
implementation.
The Biden Administration proposed cancelling the SLCM-
Background
N in the 2022 NPR, arguing that the missile was “no longer
necessary” because of the W76-2 SLBM warhead’s
The U.S. Navy first deployed a nuclear-armed sea-launched
“deterrence contribution.” The Navy’s FY2023 budget
cruise missile in the mid-1980s, when it placed the TLAM-
request eliminated funding for the SLCM-N, stating that the
N—a nuclear-armed version of the Tomahawk land-attack
missile was “cost prohibitive and the acquisition schedule
cruise missile—on surface ships and attack submarines.
would have delivered capability late to need.”
With a range of 2,500 kilometers (about 1,550 miles), the
missiles were not included in the limits in U.S.-Soviet arms
Current Status
control agreements.
The Biden Administration did not include the SLCM-N in
In 1991, at the end of the Cold War, President George H.W.
its FY2023, FY2024, or FY2025 budget requests. The
Bush announced that the United States would withdraw all
Administration’s policy statements on the FY2023 and
land-based tactical nuclear weapons (those that could travel
FY2024 NDAAs asserted that continuing the SLCM-N
less than 300 miles) from overseas bases and all sea-based
program “would divert resources and focus from higher
tactical nuclear weapons from surface ships, submarines,
modernization priorities.” Despite the Administration’s
and naval aircraft. The Navy withdrew the TLAM-N
objections, Congress has provided continued funding for
missiles by mid-1992 and eliminated the nuclear mission
the missile and the associated warhead (see Table 1).
for U.S. surface ships, but retained the option to return the
Table 1. Funding for SLCM-N ($ in millions)
TLAM-N to attack submarines. Some observers
characterized this redeployment ability as demonstrating the
Authorizations and
credibility of U.S. defense commitments to allies in Asia.
Appropriations
FY2023 FY2024
In 2010, the Obama Administration recommended that the
Authorized for SLCM-N
25.0
190.0
Navy retire the TLAM-N missiles. The 2010 NPR stated
that “this system serves a redu
Appropriated for SLCM-N
25.0
130.0
ndant purpose,” as it was one
of several weapons the United States could deploy in
Authorized for SLCM-N warhead
20.0
70.0
support of U.S. allies. The Navy completed the retirement
Appropriated for SLCM-N warhead
20.0
70.0
of these missiles in 2013.
Source: P.L. 117-263; P.L. 118-31; P.L. 117-328; P.L. 118-47; P.L.
The Trump Administration reversed this decision, arguing
118-42.
in the 2018 NPR that a nuclear-armed sea-launched cruise
missile (now known as SLCM-N) would provide the United
Section 1640 of the FY2024 NDAA (P.L. 118-31 of
States with a “non-strategic regional presence” that would
December 22, 2023) directs DOD to establish within 90
address the “need for flexible and low-yield options.”
days a “major defense acquisition program” for the SLCM-
SLCM-N was one of two systems that the 2018 NPR
N under the Undersecretary of Defense for Acquisition and
characterized as “modest supplements” that would
Sustainment (USD A&S), initiate a program to alter the
“strengthen deterrence of regional adversaries” and assure
W80-4 warhead for delivery via SLCM-N, and “ensure”
U.S. allies. The other 2018 NPR-recommended system was
that the system achieves IOC no later than September 30,
a low-yield version of the W76 nuclear warhead (known as
2034. Section 1640 also mandates recurring DOD and
the W76-2) for the Trident D5 long-range submarine-
NNSA briefings on SLCM-N program progress and a report
launched ballistic missile (SLBM). The 2018 NPR stated
due in June 2024 on the “actions required to effectively
that the W76-2 was an option for the “near-term,” while
deploy … [SLCM-N] from a Virginia class submarine and
SLCM-N would be an option implemented over “the longer
such other platforms as the Secretary [of the Navy]
term.” DOD announced the deployment of the W76-2 in
determines appropriate,” as well as potential platform
https://crsreports.congress.gov
Nuclear-Armed Sea-Launched Cruise Missile (SLCM-N)
changes, modifications to port facilities, implications for
visible generation” could provide the President with
manning, and associated costs.
additional signaling and response options in a crisis. In
April 2022 testimony, General Mark Milley, then-Chairman
USD A&S William LaPlante testified in April 2024 that in
of the Joint Chiefs of Staff, also expressed support for the
March 2024 he had directed the “Navy to establish a
SLCM-N, arguing that the President “deserves to have
[SLCM-N] program office and to begin the analysis phase.”
multiple options.” The 2023 final consensus report of the
He also stated that the Nuclear Weapons Council, a joint
Congressional Commission on the Strategic Posture of the
DOD-NNSA coordination group, is “leading a review of
United States did not explicitly endorse the SLCM-N, but
options to execute the SLCM-N program in a manner that
called for a prompt system that is “forward deployed or
balances cost, deterrence value, and risk to the [nuclear
deployable”; “survivable against preemptive attack without
modernization] program of record and the Joint Force.”
force generation day-to-day”; possesses “a range of
Finally, he advocated balancing “SLCM-N programmatic
explosive yield options, including low yield”; and is able to
manning with on-going Navy and NNSA programs”
penetrate adversary integrated air and missile defenses.
because they “draw from a limited pool of experienced
Observers have debated whether a nuclear posture that
government personnel and the same nuclear weapons
includes low-yield capabilities like the SLCM-N and the
industrial base and production enterprise.”
W76-2 and demonstrates a willingness to use nuclear
Vice Admiral Johnny Wolfe, Director of the Navy’s
weapons improves deterrence or increases the risk of
Strategic Plans and Programs, testified in April 2024 that
nuclear war. (See CRS In Focus IF11143, A Low-Yield,
funding appropriated for the SLCM-N in FY2023 “enabled
Submarine-Launched Nuclear Warhead: Overview of the
initial development of a Concept of Operations” and other
Expert Debate.)
activities to prepare for the first of three milestones in
DOD’s acquisition process. Wolfe stated in a May 2024
Arms Control
hearing that the Navy had asked Congress for “flexibility”
Policymakers have debated the potential role of SLCM-N in
to assess various options “that will give us that [SLCM-N]
arms control. The 2018 NPR linked the missile to U.S.
capability with minimum impact” on other Navy and
concerns about a new missile that Russia has deployed in
NNSA modernization priorities.
violation of the 1987 Intermediate-Range Nuclear Forces
(INF) Treaty. Although the United States withdrew from
NNSA Administrator Jill Hruby testified in April 2024 that
the treaty in 2018, the 2018 NPR stated that SLCM-N could
NNSA had established a program office that has been
provide a treaty-compliant U.S. response to Russia’s
working with the Navy and also examining the W80-4 and
violation and incentivize Russia to engage in arms control
“potentially, other warheads that will be least disruptive” to
negotiations concerning nonstrategic nuclear weapons. In
NNSA’s warhead programs. She stated in May 2024
contrast, the 2022 NPR argued that there is “uncertainty
testimony that NNSA’s FY2025 unfunded priorities list
regarding whether SLCM-N on its own would provide
includes $70 million in funding for the SLCM-N warhead.
leverage” in such negotiations. Russia has rejected
negotiations concerning its nonstrategic nuclear weapons,
Issues in the SLCM-N Debate
citing these capabilities as necessary to offset to U.S. and
NATO conventional superiority.
Deterrence Credibility and Flexibility of Options
A key issue in the SLCM-N debate is whether adding the
Operational Tradeoffs and Costs
missile to U.S. nuclear forces is necessary to credibly deter
The Biden Administration argued in a July 2023 policy
limited nuclear use by adversaries and assure allies in
statement that “deploying SLCM-N on Navy attack
Europe and the Asia-Pacific that the United States would
submarines or surface combatants would reduce capacity
protect them from nuclear coercion. The Biden
for conventional strike munitions, create additional burdens
Administration has stated that the United States has the
on naval training, maintenance, and operations, and could
ability in its “current and planned capabilities for deterring
create additional risks to the Navy’s ability to operate in
an adversary’s limited nuclear use through conventional
key regions.” In May 2024 testimony, Navy Secretary
and nuclear armaments,” including the W76-2 SLBM and
Carlos Del Toro expressed concerns about the tactical and
air-delivered weapons such as the “Air-launched Cruise
operational tradeoffs and costs of SLCM-N for the Navy.
Missile, its successor… [the LRSO], and F-35A dual-
capable aircraft that can be equipped with B61-12 nuclear
The 2022 NPR also cited the SLCM-N’s “estimated cost”
gravity bombs.”
as a tradeoff. The Navy stated in 2022 that SLCM-N
cancellation would save $199.2 million in FY2023 and $2.1
SLCM-N proponents have argued that SLCM-N’s attributes
billion over the next five years. Secretary of Defense Lloyd
are different from low-yield capabilities delivered by other
Austin III testified in April 2022 that “the marginal
means. They say that aircraft that deliver weapons would
capability that [the SLCM-N] provides is far outweighed by
need to either be “generated” (fueled, weapons-loaded, and
the cost.” A July 2023 Congressional Budget Office (CBO)
flown) from the United States, which takes time, or else
report estimated the costs of the SLCM-N and its warhead
placed in regional bases, where they could be vulnerable to
at $10 billion from 2023-2032 “if the program began in
adversary strikes. SLCM-N proponents also argue that
2024.” This amount, the CBO noted, does not include
deploying the missile on surface vessels or attack
production costs beyond 2032, or costs for system
submarines provides advantages, such as greater
integration, storage, or operations.
availability and regional presence, over deploying the W76-
2 SLBM on ballistic missile submarines.
SLCM-N supporters argue that the deterrence and
assurance benefits of SLCM-N outweigh these operational
STRATCOM Commander General Anthony Cotton
tradeoffs and costs.
reportedly wrote in 2023 that “a low-yield, non-ballistic
nuclear capability to deter, assure and respond without
This In Focus was originally authored by Amy F. Woolf,
Specialist in Nuclear Weapons Policy.
https://crsreports.congress.gov
Nuclear-Armed Sea-Launched Cruise Missile (SLCM-N)
IF12084
Anya L. Fink, Analyst in U.S. Defense Policy
Disclaimer
This document was prepared by the Congressional Research Service (CRS). CRS serves as nonpartisan shared staff to
congressional committees and Members of Congress. It operates solely at the behest of and under the direction of Congress.
Information in a CRS Report should not be relied upon for purposes other than public understanding of information that has
been provided by CRS to Members of Congress in connection with CRS’s institutional role. CRS Reports, as a work of the
United States Government, are not subject to copyright protection in the United States. Any CRS Report may be
reproduced and distributed in its entirety without permission from CRS. However, as a CRS Report may include
copyrighted images or material from a third party, you may need to obtain the permission of the copyright holder if you
wish to copy or otherwise use copyrighted material.
https://crsreports.congress.gov | IF12084 · VERSION 6 · UPDATED