The U.S. Navy has fielded the W76-2 low-yield nuclear warhead, which is used on the submarine-launched Trident II ballistic missile. The low-yield weapon is a variant of the standard W76-1 Trident II warhead, which itself was upgraded from the W76-0 standard in a program completed in December 2018. The National Nuclear Security Administration announced in January 2019 that production of the first W76-2 had begun. The requirement calls for only a small number of warheads to be modified to the low-yield configuration.
The deployment of a low-yield nuclear capability stems from the 2018 Nuclear Posture Review, which called for additional nuclear response options as a deterrent against Russia attempting to use its own low-yield nuclear weapon in a limited first-use scenario.
The House included a provision in its version of the FY20 defense authorization bill that would have prohibited the fielding of a low-yield ballistic missile warhead. House Armed Services Committee Chairman Adam Smith (D-Wash) argued that the existing U.S. nuclear arsenal already serves as a deterrent to Russia conducting a low-yield nuclear first strike, as a U.S. nuclear response could employ a high-yield weapon. “That’s the deterrent,” he said. The House provision did not make it into the final version of the defense authorization bill, allowing deployment of the low-yield warhead to move forward.
A statement from the Pentagon said that “this supplemental capability strengthens deterrence and provides the United States a prompt, more survivable low-yield strategic weapon; supports our commitment to extended deterrence; and demonstrates to potential adversaries that there is no advantage to limited nuclear employment because the United States can credibly and decisively respond to any threat scenario.”