The Department of Energy’s National Nuclear Security Administration (NNSA) completed the last production unit of the W88 Alteration 370, a program to modernize the W88 nuclear warhead over several years, NNSA announced Tuesday.
The W88 nuclear warhead entered the stockpile in late 1988 and is deployed in the U.S. Navy’s Ohio-class Trident II D5 Submarine-Launched Ballistic Missile system. The W88 Alt 370 includes numerous updates to address aging concerns and enhance nuclear security, NNSA said in the release.
The Navy coordinated with personnel from Los Alamos National Laboratory and Sandia National Laboratories, both in New Mexico, the Pantex Plant in Texas, the Y-12 National Security Complex in Tennessee and the Kansas City National Security Campus. The Navy and the facilities are working on design, development, component production and qualification, the release said.
Now that the last unit is complete, Pantex will continue production of the W88 Alt 370 warheads and secondary components for future surveillance. With the transition to sustainment for the W88 Alt 370, staff from that program are transitioning to focusing on accelerating the nuclear-armed sea-launched cruise missile (SLCM-N) program. The SLCM-N program and W93 warheads, two of the seven ongoing warhead modernization programs within NNSA, currently are expected to achieve first production unit milestones in the early to mid-2030s.
“Completing the W88 Alt 370 is the latest instance of NNSA delivering modernized nuclear weapons to the Department of War at the pace and scale needed to fulfill our deterrence requirements,” NNSA Administrator Brandon Williams said in the release. “Achieving two LPUs for the B61-12 and W88 and the FPU for the B61-13 all within a single year demonstrates our ability to execute NNSA’s fundamental production mission.”
James McConnell, NNSA’s then-acting principal deputy administrator, said in a May Senate Armed Services Committee hearing NNSA was “on track” with W88 and would reach its last production unit “relatively soon.” Then-acting NNSA administrator Teresa Robbins said similarly, adding the warhead maintains a 100% on-time delivery rate to the Navy and would finish production by the close of fiscal 2025.
The NNSA’s 2025 Stockpile Stewardship Management Plan, released October 2024, said the program would complete production in the fourth quarter of fiscal 2025 and will transition from modernization to sustainment in fiscal 2026. A plan has not been released for fiscal 2026.
The W88 Alt 370’s first production unit was delivered July 2021, meaning four years separates the delivery of the first and last production unit.