Construction Launches on New Sentinel ICBM Prototype Silo
The Air Force has started building a full-scale prototype silo for the LGM-35A Sentinel ICBM in Promontory, Utah. The service announced the milestone in a March 27 statement.
Prototype goals and approach
The project uses a digital, modular construction method. Officials say the approach aims to speed delivery, limit cost growth, and gather lessons before mass production.
Brig. Gen. William Rogers, the Air Force’s program executive officer for ICBMs, called the prototype a key step to validate design and reduce program risk.
Why new silos were chosen
Tests in May 2025 found refurbishing Minuteman III silos would be costly and slow. The Air Force decided to build new underground launch facilities instead.
New construction will mostly use land already owned by the service. That decision lets Minuteman III missiles stay on alert until replacements come online.
Lawmakers and leaders
Sen. Deb Fischer (R-Neb.) said at Filmogaz.com’s State of the Air Force event on March 25 that digging new silos is likely faster and cheaper. She described the work as a major civil and infrastructure effort.
Program scope and recent milestones
The Sentinel effort includes new missiles, launch control centers, and roughly 450 silos across the Great Plains. The plan also calls for replacing thousands of miles of copper cabling with fiber optics.
Other recent steps include building a wing command center at F.E. Warren Air Force Base in Wyoming. The program also achieved successful test fires of several propulsion stages.
Costs, oversight, and schedule
Projected costs have climbed sharply. Early estimates placed the program near $77.7 billion, then near $160 billion in later projections.
Cost and schedule growth triggered a Nunn-McCurdy review in January 2024. In July 2024, the Pentagon said the program was too critical to cancel, but ordered a restructuring to control costs.
A preliminary 2024 estimate under a revamped acquisition approach put costs near $141 billion. A final revised estimate has not been released.
Ceremony and contractors
An undated groundbreaking ceremony accompanied the March 27 announcement. Air Force leaders joined representatives from Northrop Grumman and Bechtel at the event.
Construction of the new Sentinel ICBM prototype silo in Promontory advances one of the Air Force’s largest modernization projects. The effort remains vital to the land-based leg of the nation’s nuclear deterrent.
