The US Navy has now deployed the new W76-2 low-yield Trident submarine warhead. The first ballistic missile submarine scheduled to deploy with the new warhead was the USS Tennessee (SSBN-734)…The W76-2 warhead was first announced in the Trump administration’s Nuclear Posture Review (NPR) unveiled in February 2018. There, it was described as a capability to “help counter any mistaken perception of an exploitable ‘gap’ in U.S. regional deterrence capabilities,” a reference to Russia. The justification voiced by the administration was that the United States did not have a “prompt” and useable nuclear capability that could counter – and thus deter – Russian use of its own tactical nuclear capabilities…

We estimate that one or two of the 20 missiles on the USS Tennessee and subsequent subs will be armed with the W76-2, either singly or carrying multiple warheads. Each W76-2 is estimated to have an explosive yield of about five kilotons.* The remaining 18 missiles on each submarine like the Tennessee carry either the 90-kiloton W76-1 or the 455-kiloton W88. Each missile can carry up to eight warheads under current loading configurations…

The National Nuclear Security Administration (NNSA) has further explained that the “W76-2 will allow for tailored deterrence in the face of evolving threats” and gives the US “an assured ability to respond in kind to a low-yield nuclear attack.”

Excerpt from William M. Arkin and Hans M. Kristensen, US Deploys New Low-Yield Nuclear Submarine Warhead, FAS, Jan. 29, 2020

*The Hiroshima bomb was 15 kilotons.