CRS – A Low-Yield, Submarine-Launched Nuclear Warhead: Overview of the Expert Debate Updated September 9, 2020 – “The Trump Administration has developed a new low-yield version of the W-76 warhead for existing submarine-launched Trident II (D-5) missiles. Unclassified sources state that the current W76-1 warhead has an explosive yield of around 100 kilotons. The National Nuclear Security Administration (NNSA) has said the low-yield version, the W76-2, would be configured “for primary-only detonation.” This could mean a yield of less than 10 kilotons. Congress appropriated $65 million for the W76-2 warhead in FY2019 and $10 million to complete work in FY2020. NNSA completed the first modified warhead in February 2019 and began delivering warheads to the Navy by late 2019. The Pentagon announced that the Navy had begun to deploy the warheads on February 4,2020. Congress authorized $19.6 million in the FY2020 NDAA (P.L. 116-92) for the Navy to begin integrating the warhead into the submarine force. NNSA has not disclosed the total number of planned W76-2 warheads, although it is expected to be a very small portion of the W76 stockpile (estimated, in unclassified sources, to be around 1,300 total warheads). The Trump Administration introduced the low-yield version of the W76 warhead in the 2018 Nuclear Posture Review(NPR). It cited the need for additional “tailored” and “flexible” capabilities to address the danger of coercive nuclear use, a concept described below, by Russia and North Korea. The NPR stated that this warhead would supplement existing U.S. strategic nuclear capabilities to “enhance deterrence by denying potential adversaries any mistaken confidence that limited nuclear employment can provide a useful advantage over the United States and its allies,” and that low-yield warheads would not add to the number of deployed SLBM warheads, but would replace some “higher-yield [SLBM warheads] currently deployed.”The NPR report, and its argument in favor of a low-yield SLBM warhead, launched a debate among U.S. experts about the rationale for the development of such a warhead and the benefits and risks that might accrue from its deployment. While some argue that this warhead is a response to Russia’s so-called“escalate to de-escalate” strategy that will strengthen deterrence and raise the nuclear threshold, others contend that it will lower the threshold for U.S. use and increase the risk of nuclear war…”