The United States Air Force has reached a new milestone in the development of the LGM-35A Sentinel, a next-generation intercontinental ballistic missile (ICBM) designed to replace the aging Minuteman III system.
An inert Sentinel missile was vertically assembled at Vandenberg Space Force Base, California, in September 2026. The four-month integration effort tested how the missile’s major components and support processes work together.
The U.S. Air Force says the program is now preparing for initial flight testing in 2027. The Sentinel is currently planned to reach initial operational capability in the early 2030s, meaning it has not yet entered operational deployment.
The program is part of the United States’ broader modernization of the land-based component of its nuclear forces. The Sentinel is being developed by Northrop Grumman and is intended to eventually replace the Minuteman III fleet.
The Sentinel is being developed as the successor to the LGM-30 Minuteman III, which forms the land-based part of the U.S. nuclear triad. The modernization program involves not only the missile but also launch facilities, command systems and supporting infrastructure.
The U.S. Air Force describes Sentinel as a major modernization effort for its land-based strategic deterrent. The program is being developed with Northrop Grumman as the prime contractor.
The next major milestone is the planned 2027 flight-testing phase. Testing will provide data on the integrated system before the missile moves toward eventual operational deployment in the following decade.
The development is being closely followed because Sentinel is expected to become a long-term component of the United States’ strategic nuclear forces.
The latest milestone is significant because the program has moved beyond computer designs and individual component testing toward a fully integrated missile system. The Air Force also completed a design review connected with the planned flight-test campaign.
The first Sentinel flight tests are planned for 2027. The missile is still in development and has not entered operational deployment. The Air Force currently expects initial capability in the early 2030s.