https://crsreports.congress.gov
Updated July 19, 2024
Nuclear-Armed Sea-Launched Cruise Missile (SLCM-N)
Congress and the executive branch have debated the merits
of a new nuclear-armed sea-launched cruise missile
(SLCM-N) since the weapon was first proposed by the
Trump Administration in 2018. The Biden Administration
proposed cancelling the SLCM-N program following its
2022 Nuclear Posture Review (NPR), a periodic assessment
of U.S. nuclear policy. Congress has provided continued
funding for the SLCM-N and its warhead; the FY2024
National Defense Authorization Act (NDAA) requires the
executive branch to ensure SLCM-N initial operational
capability (IOC). Since the FY2024 NDAA, the
Administration has taken steps to begin SLCM-N program
implementation.
Background
The U.S. Navy first deployed a nuclear-armed sea-launched
cruise missile in the mid-1980s, when it placed the TLAM-
N—a nuclear-armed version of the Tomahawk land-attack
cruise missile—on surface ships and attack submarines.
With a range of 2,500 kilometers (about 1,550 miles), the
missiles were not included in the limits in U.S.-Soviet arms
control agreements.
In 1991, at the end of the Cold War, President George H.W.
Bush announced that the United States would withdraw all
land-based tactical nuclear weapons (those that could travel
less than 300 miles) from overseas bases and all sea-based
tactical nuclear weapons from surface ships, submarines,
and naval aircraft. The Navy withdrew the TLAM-N
missiles by mid-1992 and eliminated the nuclear mission
for U.S. surface ships, but retained the option to return the
TLAM-N to attack submarines. Some observers
characterized this redeployment ability as demonstrating the
credibility of U.S. defense commitments to allies in Asia.
In 2010, the Obama Administration recommended that the
Navy retire the TLAM-N missiles. The 2010 NPR stated
that “this system serves a redundant purpose,” as it was one
of several weapons the United States could deploy in
support of U.S. allies. The Navy completed the retirement
of these missiles in 2013.
The Trump Administration reversed this decision, arguing
in the 2018 NPR that a nuclear-armed sea-launched cruise
missile (now known as SLCM-N) would provide the United
States with a “non-strategic regional presence” that would
address the “need for flexible and low-yield options.”
SLCM-N was one of two systems that the 2018 NPR
characterized as “modest supplements” that would
“strengthen deterrence of regional adversaries” and assure
U.S. allies. The other 2018 NPR-recommended system was
a low-yield version of the W76 nuclear warhead (known as
the W76-2) for the Trident D5 long-range submarine-
launched ballistic missile (SLBM). The 2018 NPR stated
that the W76-2 was an option for the “near-term,” while
SLCM-N would be an option implemented over “the longer
term.” DOD announced the deployment of the W76-2 in
2020. At the same time, the Navy conducted an Analysis of
Alternatives on the SLCM-N.
In its FY2022 budget request, the Biden Administration
sought $5.2 million for Department of Defense (DOD)
research and development work on the SLCM-N. It also
requested $10 million for the National Nuclear Security
Administration (NNSA) to study adapting the W80-4
nuclear warhead, intended for the Long-Range Standoff
Weapon (LRSO) air-launched cruise missile, for delivery
carried by the SLCM-N. The Administration also stated that
it would review the program in the 2022 NPR.
The Biden Administration proposed cancelling the SLCM-
N in the 2022 NPR, arguing that the missile was “no longer
necessary” because of the W76-2 SLBM warhead’s
“deterrence contribution.” The Navy’s FY2023 budget
request eliminated funding for the SLCM-N, stating that the
missile was “cost prohibitive and the acquisition schedule
would have delivered capability late to need.”
Current Status
The Biden Administration did not include the SLCM-N in
its FY2023, FY2024, or FY2025 budget requests. The
Administration’s policy statements on the FY2023 and
FY2024 NDAAs asserted that continuing the SLCM-N
program “would divert resources and focus from higher
modernization priorities.” Despite the Administration’s
objections, Congress has provided continued funding for
the missile and the associated warhead (see Table 1).
Table 1. Funding for SLCM-N ($ in millions)
