Sentinel to have new silos, Air Force leaders tell town halls

April 18, 2025

By Exchange Monitor

The Northrop Grumman LGM-35A Sentinel intercontinental ballistic missile is to have new silos, U.S. Air Force leaders told community leaders during town halls in Kimball, Neb. and Pine Bluffs, Wyo. early April.

The Sentinel intercontinental ballistic missile (ICBM) has a significantly larger design than its predecessor 1960s-era Minuteman missile series, including the Boeing-made Minuteman III. The Minuteman “silos are already really old so if we use them for Sentinel, they are going to be over a century old,” Col. James Rodriguez, Sentinel program infrastructure and deployment division director, said on Apr. 1. “There were a number of other issues that were driving costs to be quite large, and it was becoming prolifically expensive to try to renovate them, so sometimes it is just cheaper to build something new.”

Air Force leaders have previously not given a straight answer when asked whether Sentinel would need new silos and have downplayed the significance of new silo construction.

The provision of multiple warheads, countermeasures, and increased range means the Sentinel design is significantly larger than that of the current Boeing Minuteman III.

In February, Sen. Angus King (I-Me.), the ranking member of the Senate Armed Services Committee’s strategic forces panel, said that he believed that the Air Force would have to build new silos to house Sentinel.

The Air Force fielded 450 Minuteman siloes between 1962 and 1967, of which 50 are decommissioned but may be brought back for future testing. Experts have said that placing Sentinel in Minuteman silos may lead to several degrees of tilt in such silos.

Sen. Kevin Cramer (R-N.D.) suggested this month that the Air Force may be able to re-use some Minuteman III silos for Sentinel and that the Air Force is increasingly discussing possible concurrent upgrades to house Sentinel at the three ICBM missile wings under Malmstrom AFB, Mont., F.E. Warren AFB, Wyo., and Minot AFB, N.D.

“To the degree that it’s possible yet to modify the design of Sentinel to utilize existing silos, it would be a tremendous opportunity,” Cramer said. “We’ll see. Some of them [silos] are gonna have to be [replaced]. Some of them are full of water.”

The Air Force plan has been to conduct sequential upgrades at the bases with Minot being the third and final base. Air Force Global Strike Command (AFGSC) had planned to “renovate all 450 existing [Minuteman] launch facilities in the missile fields to like-new condition.”

Air Force Maj. Gen. Colin Connor, who heads the Sentinel Site Activation Task Force in his position as director of ICBM Modernization at AFGSC at Barksdale AFB, La., told the Pine Bluffs town hall that the Air Force plans to begin digging up the old, Hardened Intersite Cable System (HICS) copper wires for Minuteman III in 2027 to replace them with fiber optic cables for Sentinel by 2030.