The US Air Force and Northrop Grumman broke ground on a prototype launch silo for the LGM-35A Sentinel intercontinental ballistic missile on February 13, 2026, at Northrop Grumman’s Strategic Missile Test and Production Complex in Promontory, Utah.
A new silo design, built from scratch
The prototype is intended to enable engineers to test and refine modern construction techniques and validate the new silo design before work begins in operational missile fields. Under the restructured program, Sentinel will no longer reuse the existing Minuteman III silos, which are already around 60 years old. Had those silos been refurbished under the original plan, they would have been approaching 150 years of age by the end of Sentinel’s projected 70-year service life.
A second round of prototyping activity is planned for this summer at F.E. Warren Air Force Base in Wyoming, where teams will test utility corridor construction methods to streamline the installation of thousands of miles of secure infrastructure.
Infrastructure on a national scale
The infrastructure scope remains significant. The US Air Force plans to build 24 launch centers and three missile wing command centers, spread across 32,000 square miles in five states and connected by roughly 5,000 miles of fiber-optic cable. Construction on the first of those Wing Command Centers is already underway at F.E. Warren, and test facilities are being erected at Vandenberg Space Force Base to support the program’s upcoming flight test campaign.
As for the missile itself, progress has continued in parallel. The US Air Force and Northrop Grumman completed a full-scale qualification test of Sentinel’s Stage-2 solid rocket motor in July 2025, following a successful Stage-1 qualification in March 2025. Late in 2025, the program assembled its first complete three-stage ground test missile, which will be used for transportation and emplacement pathfinder activities ahead of the first flight. The first missile pad launch is currently planned for 2027.
A program reshaped by cost overruns
The groundbreaking comes as the US Air Force works to complete a broad restructuring of the Sentinel program, triggered by a Nunn-McCurdy Act breach in 2024 after the program’s estimated costs more than doubled from the original $77.7 billion contract awarded to Northrop Grumman in 2020.
Officials are now executing a transformed acquisition strategy, aiming to complete the restructure and reach a Milestone B decision by the end of 2026, with an initial operational capability targeted for the early 2030s. A revised cost estimate for the program is not expected until the end of 2026.
Minuteman III transition underway
The phased handover from the Minuteman III is already underway. In September 2025, Air Force Global Strike Command took the first Minuteman III silo offline as part of a carefully sequenced decommissioning effort. Site Activation Task Force detachments have been established at F.E. Warren, Malmstrom Air Force Base in Montana, Minot Air Force Base in North Dakota, and Vandenberg Space Force Base.
Officials have estimated a minimum 15-year overlap between the first Sentinel silo going online and the last Minuteman III being decommissioned.