The United States is forced to build new silos for promising Sentinel ICBMs

The problematic project of the promising LGM-35A Sentinel intercontinental ballistic missile will require the construction of new launch silos despite the expectation of using the old infrastructure.

A US Air Force representative shared this with Air Force Times.

The Air Force will have to build completely new silos for the LGM-35A Sentinel intercontinental nuclear warheads, which will be another complication and cause a rise in the cost of the US nuclear modernization program, which has already gone beyond project costs and deadlines.

The preliminary calculation of the Air Force Command was to modernize the existing silos that housed the Minuteman III intercontinental ballistic missiles to accommodate the new Sentinel missiles. However, practical studies have revealed several problems with this approach.

The representative said that tests at Vandenberg Space Force Base in California showed that it was not feasible to integrate Sentinel into old mine complexes due to a number of subsequent problems that would lead to further delays and budget overruns.

“As the [Sentinel] program continues to undergo restructuring activities, the Air Force analysis continues to confirm unacceptable risks to cost, schedule and weapon system performance stemming from the original baseline strategy of converting Minuteman III silos,” an Air Force spokesperson said in an email Tuesday. “Additionally, we have data based on a test launch facility conversion project at Vandenberg Space Force Base that validated the implications of unknown site conditions with significant cost and schedule growth.

“To mitigate this and other risks, the Air Force plans to build new missile silos on predominantly Air Force-owned real estate, which means reusing the existing missile sites but not the 55-year-old silos,” the spokesperson continued.

As of 2025, the U.S. Air Force operates 400 silo-based launchers for Minuteman III intercontinental ballistic missiles (ICBMs). In addition, there are another 50 backup silos that are maintained on high alert to accommodate additional missiles if needed, bringing the total number to 450 silos.

The ICBM launchers are organized into groups of 10 silos, which a separate Launch Control Center controls. All of them are located at three Air Force facilities:

• 341st Missile Squadron at Malmstrom Air Force Base in Montana
• 91st Missile Squadron at Minot Air Force Base in North Dakota
• 90th Missile Squadron at F.E. Warren Air Force Base, covering parts of Wyoming, Colorado, and Nebraska

The transition from the old analog control architecture to digital Sentinel systems and the development of new silo installations actually means a complete rebuilding of the infrastructure of the ground-based component of the US nuclear triad, which entails enormous financial costs.

Gen. Thomas Bussier, head of the Air Force’s Global Strike Command, said this week that the agency is still studying the structure of the Sentinel program and looking for ways to improve it. He said the department is currently considering reusing land near the Minuteman mines, though not the mines themselves. Other federally owned land is also being studied to expand the ICBM deployment.

Assessing the scale of the project, Bussier compared its complexity to the construction of the national highway network during the Eisenhower era, emphasizing that implementation would be very difficult.

Earlier, the Sentinel program had already faced a significant cost increase and delay in implementation. And in April, a powerful explosion destroyed a building at one of Northrop Grumman’s facilities involved in the missile tests.