On Friday, March 27, 2026, U.S. company Northrop Grumman announced that on February 13, together with the U.S. Air Force (USAF) and Bechtel Corporation, it began construction of a full-scale prototype silo for the LGM-35A Sentinel intercontinental ballistic missile (ICBM) in Promontory, Utah.
Photo: Northrop Grumman
The facility will serve as a central element of a new modular underground launch silo infrastructure concept developed by Northrop Grumman and Bechtel Corporation. It will help accelerate the prototyping and design validation phase, as well as test techniques for future sustainment of 450 operational silos and reduce operating costs.
Construction began with a ceremonial groundbreaking by representatives of the involved parties three months after the completion of the concept review phase. The facility in Promontory will enable the development of a modular, repeatable silo construction method, which will accelerate the schedule and reduce risk.
Sarah Willoughby, vice president and general manager, Strategic Deterrent Systems, Northrop Grumman:
“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.”
Mike Costas, a Bechtel Senior Vice President and General Manager of Defense and Space for Bechtel’s Nuclear, Security, and Environmental, global business unit:
“We are honored to be a part of the Sentinel mission to deliver the next generation of national security. The prototype missile silo builds the foundation needed for us to be successful in the field. It builds confidence in our execution plans, while mitigating risks to delivery.”
Image: Northrop Grumman
The next-generation launch silo is intended to be more durable, secure, cost-effective, and easier to maintain than the LGM-30G Minuteman III system.
Meanwhile, on February 17 of this year, the USAF press service reported that the GBSD (Ground Based Strategic Deterrent) program, under which Northrop Grumman is developing the LGM-35A Sentinel system, is back on track. By the end of the year, a Milestone B decision and the construction of a full prototype are expected to be announced, followed next year by a ballistic missile test from Vandenberg Space Force Base in California.
Last fall, three missile stages were assembled and a digital twin model was completed. In September of last year, the program passed a critical design review of the Sentinel Launch Support System, which will support all tests and operational launches throughout the system’s service life.
This summer, construction work at F.E. Warren Air Force Base in Wyoming will enable validation of innovative methods for building weapon system corridors. Meanwhile, construction of foundations for fixed facilities is already underway. The first of three new missile wing command centers is taking shape at F.E. Warren, while key test facilities are being built at Vandenberg.
In total, more than 10,000 people across the United States will be involved in the GBSD program. According to the USAF’s original plans, the LGM-35A Sentinel missiles are to ensure continuity of strategic deterrence and are expected to cost less than extending the service life of the current system, which consists of aging LGM-30G Minuteman III missiles. Replacing missiles dating back to the 1970s will modernize the land-based leg of the nuclear triad and bring to an end more than 60 years of Minuteman service.
We’ve broken ground on a Sentinel launch silo prototype at our facility in Utah. The new design concept is expected to reduce risk, accelerate fielding, prioritize future maintainability and drive cost savings for the program.
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— Northrop Grumman (@NGCNews) March 27, 2026