Newly released photos show U.S. Air Force personnel conducting depot-level maintenance on Minuteman III nuclear-capable intercontinental ballistic missiles, as the U.S. modernizes its aging land-based nuclear arsenal.

Nuclear Arsenal Still on Alert

The Minuteman III ICBMs, operational since 1970, remain a key part of the U.S. nuclear triad alongside submarines and bombers. Deployed across silos in Colorado, Montana, Nebraska, North Dakota, and Wyoming, the fleet consists of 400 missiles capable of reaching over 6,000 miles.

Each missile carries one nuclear warhead but can be equipped with multiple, according to the Federation of American Scientists.

Depot Maintenance and Modernization

Photos from Hill Air Force Base in Utah show technicians from the 582nd Missile Maintenance Squadron servicing booster sections of the Minuteman III system. The base is responsible for “programmed depot maintenance,” including defect correction, overhaul, and modifications that field units cannot perform.

This follows a May 21 test in which an unarmed Minuteman III flew 4,200 miles from California to the Marshall Islands to validate strategic readiness.

Sentinel ICBM to Replace Minuteman

While the Minuteman III system underwent major upgrades in 2015, it is scheduled for phased retirement. The Sentinel ICBM will replace the system on a one-for-one basis, ensuring a land-based nuclear strike capability through 2075.

According to the U.S. Air Force, the new system promises enhanced security, efficiency, and modern command integration.