The schedule for one of Sentinel’s nuclear warheads will not change until at least the end of the Air Force’s review of the budget-busting missile, the head of the National Nuclear Security Administration said Tuesday.

The civilian agency will stick to its current schedule for the W87-1 warhead throughout the Air Force’s ongoing Nunn-McCurdy review of the silo-based intercontinental ballistic missile, “or perhaps beyond,” Jill Hruby, administrator of the National Nuclear Security Administration (NNSA), said during a hearing in the House.

Hruby was responding to questioning by Rep. Scott DesJarlais (R-Tenn.) in the House Armed Services strategic forces subcommittee.

“Our only real concern is whether flight tests will stay on schedule,” Hruby said during the hearing.

In its fiscal year 2025 budget request, the Air Force said Sentinel’s first development test flight would launch in February 2026. Prior to the service’s January disclosure of Sentinel’s Nunn-McCurdy breach, the first test flight was penciled in for December 2023.

In her prepared testimony, Hruby said W87-1’s first production unit, a proof-of-concept article that will be dismantled and examined to prove the design is ready for mass production, should be done by September 2032. Inert versions of the weapon could fly before then.

Sentinel was to replace the current fleet of Minuteman III missiles beginning in 2030 or so. In January, the Air Force in January told Congress that the Sentinel program had a 37% unit-cost breach, well over the 25% unit cost threshold that triggers a mandatory Nunn-McCurdy review, under a law named for its authors.

The bill for the entire Sentinel program, run by prime contractor Northrop Grumman, Falls Church, Va., rose to an estimated $125 billion or so compared with $95 billion previously. The per-unit cost for missiles rose to $162 million from $118 million in 2020. 

The Air Force has not said when it will finish its Nunn-McCurdy review.

The first Sentinel missiles deployed will carry W87-0 warheads: weapons taken from Minuteman III missiles adapted for use on the replacement missile.

Later Sentinels will carry a W87-1, a replacement for Minuteman II’s W78. The W87-1 will be a newly manufactured warhead with a fresh plutonium core from the Los Alamos NAtional Laboratory in New Mexico.

Los Alamos planned to start casting war-ready versions of these W87-1 cores, called plutonium pits, by December, then ramp up to casting 30 a year by 2028 or so, officials said in February.