GAO watchdog says first Sentinel ICBM years behind schedule, won’t fly until 2028

The Air Force wants to replace the 50-year-old Minuteman III intercontinental ballistic missile, a key element of the nation’s strategic nuclear deterrence, with the new LGM-35 Sentinel ICBM. But the new program is years behind schedule and proving much more costly than originally projected.

The Sentinel program is undergoing a major overhaul after triggering a Nunn-McCurdy breach in 2024. It mandates notifying Congress when a program’s costs grow by 25% or more over its current baseline.

The delay means the first flight of a Sentinel missile is now expected in March 2028, four years after it was originally intended to launch, and the Minuteman missiles will have to be used much longer than intended, according to a report released this week by the Government Accountability Office.

“Sentinel delays mean the Air Force will need to operate the aging Minuteman III longer than planned,” the GAO said.

The Pentagon estimates that the program will cost at least $141 billion, up from the original $78 billion, but the actual costs remain uncertain.

The Nunn-McCurdy breach has provided the Air Force with an opportunity to address fundamental issues with the program, including resolving issues with key design tools, performance requirements, and finalizing the design of the launch center, the GAO analysts said.

“Further program outcomes will depend on the extent to which the Air Force takes advantage of this opportunity to correct earlier mistakes,” the congressional watchdog said.

The Air Force has yet to develop a risk-management plan for the transition from the Minuteman III to the Sentinel program, which the GAO called “the most complex project the service has ever undertaken.”

“A very large project that costs $1 billion or more, affects one million or more people, and runs for years may be referred to as a ’megaproject,’” the GAO said. “Megaprojects are extremely risky ventures, notoriously difficult to manage, and often fail to achieve their original objectives.”


The Minuteman III system consists of more than 600 facilities across five states, including missile silos and command bunkers. The GAO said all of that must be replaced as part of the upgrade.