The Air Force’s next-generation nuclear-tipped, silo-based intercontinental ballistic missile will continue but will be drastically restructured amid further cost increases and schedule delays announced Monday by the Department of Defense.
The new overall cost estimate for Sentinel is $140.9 billion: 81% higher than the September 2020 estimate when the program entered its manufacturing phase and about 13% higher than the Pentagon’s estimate from January, when it disclosed the overrun as required by the law known as Nunn-McCurdy.
Among the big changes, the Department of Defense said it rescinded its 2020 decision to initiate Sentinel’s engineering and manufacturing development phase (EMD), the point in Pentagon program management where a weapon is built. Sentinel was supposed to be deployed in 2030 or so.
Monday’s announcement followed the program review triggered by Sentinel’s critical Nunn-McCurdy breach, which the Air Force disclosed in January. A breach happens when a program is at least 25% above the program acquisition unit cost compared with the program baseline.
In January, the unit cost per missile and other items was pegged at $162 million, 37% higher than the $118 cost estimate at the time of the EMD approval.
For LGM-35A Sentinel, that was set in September 2020, when prime contractor Northrop Grumman, which effectively squeezed Boeing out of a competition to build the next land-based intercontinental ballistic missile, got Milestone B approval to enter the engineering, manufacturing and development phase of the program.
The new unit cost is $214 million, Andrew Hunter, assistant secretary of the Air Force for acquisition, technology, and logistics, confirmed during a virtual media roundtable on Monday afternoon.
Under Nunn-McCurdy, Sentinel, formerly the Ground Based Strategic Deterrent, would have to be terminated unless it met five criteria following the breach review. According to the Air Force, it did.
The Pentagon has said the cost breach has less to do with the missile than the command-and-control segment, which the department said “includes the launch facilities, launch centers, and the process, duration, staffing, and facilities to execute the conversion from Minuteman III to Sentinel.”
Minuteman III, made by Boeing, is the current ICBM that forms the land-based portion of the U.S. nuclear arsenal.
The first Sentinel missiles were to be fitted with W87-0 warheads provided by the National Nuclear Security Administration (NNSA). These weapons would be pulled off of Minuteman III missiles and adapted for use on Sentinel.
Later Sentinel missiles would use W87-1 warheads: newly manufactured weapons designed by the Lawrence Livermore National Laboratory in California, with a freshly cast plutonium pit from the Los Alamos National Laboratory in New Mexico. W87-1 would replace the W78 now used on Minuteman III.
In its fiscal year 2025 budget request, released in March, 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.
A version of this story first appeared in Weapons Complex Morning Briefing affiliate publication Defense Daily.
