Construction of Sentinel ICBM silo prototype begins in Utah

Construction has commenced on a full-scale prototype launch silo for the LGM-35A Sentinel intercontinental ballistic missile (ICBM) in Promontory, Utah.

The project, managed by Northrop Grumman in partnership with Bechtel, is intended to validate a modular and repeatable approach to silo construction, which officials say will help reduce costs and accelerate deployment.

Northrop Grumman strategic deterrent systems vice president and general manager Sarah Willoughby said: “Sentinel is a national security priority and proving out the launch silo concept is critical to creating a repeatable approach that will accelerate deployment of a fully fielded Sentinel system.

“The shift in Sentinel silo construction will improve quality and provide a secure, survivable and cost-effective launch silo that is more efficient to maintain.” 

The prototype aims to demonstrate the structural integrity and construction method of the new modular infrastructure, which Northrop Grumman and Bechtel developed to support the eventual fielding of 450 launch silos.

The design seeks to ease future maintenance and streamline both initial construction and long-term operation compared to legacy Minuteman III facilities.

Recent programme progress includes ongoing construction of a new Wing Command Centre at F.E. Warren Air Force Base in Wyoming and successful tests of all major propulsive elements for the Sentinel missile system.

Northrop Grumman has test-fired each missile stage and completed a hot fire assessment of the post-boost propulsion system to address technical risks ahead of a scheduled 2027 flight test.

According to Northrop Grumman, within three months of the Air Force’s concept review, work began on the prototype launch tube.

The company expects its construction approach to compress the typically lengthy development timeline for silos, thereby reducing risk and supporting timely fielding.

The Sentinel programme focuses on replacing rather than refurbishing existing Minuteman III infrastructure.

This shift is intended to maintain continuous alert coverage throughout the transition while supporting updated system requirements.

The modular approach is designed for survivability, security, cost-efficiency, and easy upkeep.

Efforts across the Sentinel programme office, Air Force Global Strike Command, and US Strategic Command aim to provide infrastructure that meets operational needs well into the future.

The Department of War projects that initial operational capability will be achieved in the early 2030s.

Northrop Grumman oversees a nationwide team under contract for engineering and manufacturing development of Sentinel.

The Sentinel programme is expected to remain viable through 2075 as part of modernising the nation’s strategic nuclear triad with updated technology and infrastructure designed to reduce long-term costs and enhance maintainability.

Air Force Global Strike Command commander general S.L. Davis said: “Sentinel is foundational to our no-fail mission, and this work helps deliver a weapons system that is more safe, more secure, and more effective on day one. This modernisation effort will provide uninterrupted deterrence and ensure the readiness of the ICBM force for decades to come.”