NNSA details US nuclear warhead modernisation timeframes

An artist's portrayal of the Northrop Grumman LGM-35A Sentinel intercontinental ballistic missile. (Northrop Grumman)

The US is undergoing large-scale recapitalisation of its nuclear deterrent capability, with warheads central in this process: five warhead programmes are under way, two of which are in production and in-service phases, and three programmes are in development, according to a Department of Energy (DoE) National Nuclear Security Administration (NNSA) annual report.

The two in production are the B61-12 air-launched gravity bomb, which is replacing four older, in-service B61 variants; and the W88 Alteration (Alt) 370 submarine-launched ballistic missile (SLBM) warhead, which is replacing the W88, the larger-yield warhead fitted to the US Navy's (USN's) Trident D5 SLBM, the NNSA said in its fiscal year (FY) 2024 Stockpile Stewardship and Management Plan (SSMP) report presented to Congress on 27 November.

For B61-12, the first production unit (FPU) was delivered in November 2021, full-scale production (Phase 6.6) commenced in 2022, and (as the SSMP confirmed) the warhead is cleared for operational deployment on the B-2 Spirit strategic bomber.

In 2022 initial operational capability for W88 Alt 370 was achieved for the navy's in-service Ohio-class nuclear-powered ballistic missile submarines (SSBNs) through delivery of an unspecified number of re-entry vehicle (RV) assemblies. In June 2022 the programme commenced full-scale production.

Both weapons have been formally accepted into the operational stockpile by the Nuclear Weapons Council. Near-term NNSA focus includes full delivery of these programmes.