The following is the April 25, 2022, Congressional Research Service In Focus report, Nuclear-Armed Sea-Launched Cruise Missile (SLCM-N).
From the report
In its FY2023 budget request, the Navy eliminated funding for research and development into a new nuclear-armed sea-launched cruise missile (SLCM-N). The Navy indicated that the program was “cost prohibitive and the acquisition schedule would have delivered capability late to need.” According to the Navy, this cancellation would save $199.2 million in FY2023 and $2.1 billion over the next five years. Press reports also indicate that this decision is supported in the Biden Administration’s Nuclear Posture Review (NPR).
The United States first deployed a nuclear-armed version of the Tomahawk land-attack cruise missile (TLAM-N) in the mid-1980s. The missiles were deployed on both surface ships and attack submarines. With a range of 2,500 kilometers (around 1,550 miles), the missiles were not considered part of the U.S. strategic nuclear forces (see CRS In Focus IF10519, Defense Primer: Strategic Nuclear Forces, by Amy F. Woolf) and, therefore, did not count under the limits on warheads or delivery vehicles in U.S.-Soviet arms control agreements.
In September 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 U.S. surface ships, submarines, and naval aircraft. The Navy withdrew the TLAM-N missiles by mid-1992. It eliminated the nuclear mission for U.S. surface ships but could have returned TLAM-N to attack submarines. Many viewed the U.S. ability to return these missiles to deployment on short notice as a part of the U.S. effort to reassure allies in Asia of the U.S. commitment to their security.
In 2010, the Obama Administration’s NPR recommended that the Navy retire the TLAM-N missiles. It indicated that “this system serves a redundant purpose in the U.S. nuclear stockpile” as one of several weapons the United States could deploy in support of U.S. allies. It concluded that because “the deterrence and assurance roles of TLAM-N can be adequately substituted by these other means,” the United States could continue to support allies in Asia without maintaining the capability to redeploy TLAM-N missiles. The Navy completed the retirement of these missiles by 2013.
The Trump Administration, in effect, reversed this decision, noting in the 2018 NPR that a nuclear-armed sea-launched cruise missile (now known as SLCM-N) would provide the United States with “a needed non-strategic regional presence” that would address “the increasing need for flexible and low-yield options.” This is intended to strengthen deterrence of regional adversaries and assure allies of the U.S. commitment to their defense. The NPR also indicated that SLCM-N could serve as a response to Russia’s violation of the 1987 Intermediate-Range Nuclear Forces (INF) Treaty and provide Russia with an incentive to negotiate reductions in its nonstrategic nuclear weapons.
SLCM-N was one of two systems that the 2018 NPR identified as a way to “strengthen deterrence of regional adversaries.” The Navy deployed a low-yield version (with less than 10 kilotons, rather than 100 kilotons, of explosive power) of the W76 warhead on its long-range submarine-launched ballistic missile in 2019 (see CRS In Focus IF11143, A Low-Yield, Submarine-Launched Nuclear Warhead: Overview of the Expert Debate, by Amy F. Woolf). The Navy conducted an Analysis of Alternatives in support of the SLCM-N from 2019-2021, and expected to begin the development of the missile in 2022 and achieve operational capability late in the 2020s.
In its FY2022 budget request, the Biden Administration sought $5.2 million in DOD funding for research and development into the missile and $10 million for the National Nuclear Security Administration (NNSA) to work on a warhead that would be carried by the SLCM-N. At the same time, the Administration indicated that it would review the program as a part of its NPR.
After the Navy eliminated funding for SLCM-N in its FY2023 budget request, some Members of Congress asked General Milley, the Chairman of the Joint Chiefs of Staff, and Secretary of Defense Austin whether they supported the decision. General Milley said he continued to support SLCM-N because the President “deserves to have multiple options to deal with national security situations.” But he later noted that the United States has “lots of options and we have a significant nuclear capability.” Secretary Austin also recognized the value of the SLCM-N but stated that “the marginal capability that this provides is far outweighed by the cost.”
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