Nuclear-Armed Sea-Launched Cruise Missile (SLCM-N)

Nuclear-Armed Sea-Launched Cruise Missile (SLCM-N)

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changes, modifications to port facilities, implications for manning, and associated costs.

USD A&S William LaPlante testified in April 2024 that in March 2024 he had directed the “Navy to establish a [SLCM-N] program office and to begin the analysis phase.” He also stated that the Nuclear Weapons Council, a joint DOD-NNSA coordination group, is “leading a review of options to execute the SLCM-N program in a manner that balances cost, deterrence value, and risk to the [nuclear modernization] program of record and the Joint Force.” Finally, he advocated balancing “SLCM-N programmatic manning with on-going Navy and NNSA programs” because they “draw from a limited pool of experienced government personnel and the same nuclear weapons industrial base and production enterprise.”

Vice Admiral Johnny Wolfe, Director of the Navy’s Strategic Plans and Programs, testified in April 2024 that funding appropriated for the SLCM-N in FY2023 “enabled initial development of a Concept of Operations” and other activities to prepare for the first of three milestones in DOD’s acquisition process. Wolfe stated in a May 2024 hearing that the Navy had asked Congress for “flexibility” to assess various options “that will give us that [SLCM-N] capability with minimum impact” on other Navy and NNSA modernization priorities.

NNSA Administrator Jill Hruby testified in April 2024 that NNSA had established a program office that has been working with the Navy and also examining the W80-4 and “potentially, other warheads that will be least disruptive” to NNSA’s warhead programs. She stated in May 2024 testimony that NNSA’s FY2025 unfunded priorities list includes $70 million in funding for the SLCM-N warhead.

Issues in the SLCM-N Debate

Deterrence Credibility and Flexibility of Options A key issue in the SLCM-N debate is whether adding the missile to U.S. nuclear forces is necessary to credibly deter limited nuclear use by adversaries and assure allies in Europe and the Asia-Pacific that the United States would protect them from nuclear coercion. The Biden Administration has stated that the United States has the ability in its “current and planned capabilities for deterring an adversary’s limited nuclear use through conventional and nuclear armaments,” including the W76-2 SLBM and air-delivered weapons such as the “Air-launched Cruise Missile, its successor… [the LRSO], and F-35A dual- capable aircraft that can be equipped with B61-12 nuclear gravity bombs.”

SLCM-N proponents have argued that SLCM-N’s attributes are different from low-yield capabilities delivered by other means. They say that aircraft that deliver weapons would need to either be “generated” (fueled, weapons-loaded, and flown) from the United States, which takes time, or else placed in regional bases, where they could be vulnerable to adversary strikes. SLCM-N proponents also argue that deploying the missile on surface vessels or attack submarines provides advantages, such as greater availability and regional presence, over deploying the W76- 2 SLBM on ballistic missile submarines.

STRATCOM Commander General Anthony Cotton reportedly wrote in 2023 that “a low-yield, non-ballistic nuclear capability to deter, assure and respond without

visible generation” could provide the President with additional signaling and response options in a crisis. In April 2022 testimony, General Mark Milley, then-Chairman of the Joint Chiefs of Staff, also expressed support for the SLCM-N, arguing that the President “deserves to have multiple options.” The 2023 final consensus report of the Congressional Commission on the Strategic Posture of the United States did not explicitly endorse the SLCM-N, but called for a prompt system that is “forward deployed or deployable”; “survivable against preemptive attack without force generation day-to-day”; possesses “a range of explosive yield options, including low yield”; and is able to penetrate adversary integrated air and missile defenses.

Observers have debated whether a nuclear posture that includes low-yield capabilities like the SLCM-N and the W76-2 and demonstrates a willingness to use nuclear weapons improves deterrence or increases the risk of nuclear war. (See CRS In Focus IF11143, A Low-Yield, Submarine-Launched Nuclear Warhead: Overview of the Expert Debate.)

Arms Control Policymakers have debated the potential role of SLCM-N in arms control. The 2018 NPR linked the missile to U.S. concerns about a new missile that Russia has deployed in violation of the 1987 Intermediate-Range Nuclear Forces (INF) Treaty. Although the United States withdrew from the treaty in 2018, the 2018 NPR stated that SLCM-N could provide a treaty-compliant U.S. response to Russia’s violation and incentivize Russia to engage in arms control negotiations concerning nonstrategic nuclear weapons. In contrast, the 2022 NPR argued that there is “uncertainty regarding whether SLCM-N on its own would provide leverage” in such negotiations. Russia has rejected negotiations concerning its nonstrategic nuclear weapons, citing these capabilities as necessary to offset to U.S. and NATO conventional superiority.

Operational Tradeoffs and Costs The Biden Administration argued in a July 2023 policy statement that “deploying SLCM-N on Navy attack submarines or surface combatants would reduce capacity for conventional strike munitions, create additional burdens on naval training, maintenance, and operations, and could create additional risks to the Navy’s ability to operate in key regions.” In May 2024 testimony, Navy Secretary Carlos Del Toro expressed concerns about the tactical and operational tradeoffs and costs of SLCM-N for the Navy.

The 2022 NPR also cited the SLCM-N’s “estimated cost” as a tradeoff. The Navy stated in 2022 that SLCM-N cancellation would save $199.2 million in FY2023 and $2.1 billion over the next five years. Secretary of Defense Lloyd Austin III testified in April 2022 that “the marginal capability that [the SLCM-N] provides is far outweighed by the cost.” A July 2023 Congressional Budget Office (CBO) report estimated the costs of the SLCM-N and its warhead at $10 billion from 2023-2032 “if the program began in 2024.” This amount, the CBO noted, does not include production costs beyond 2032, or costs for system integration, storage, or operations.

SLCM-N supporters argue that the deterrence and assurance benefits of SLCM-N outweigh these operational tradeoffs and costs.

This In Focus was originally authored by Amy F. Woolf, Specialist in Nuclear Weapons Policy.