Missile LGM-35 Sentinel

The LGM-35 Sentinel program, initially known as the Ground Based Strategic Deterrent (GBSD), originated from a 2010 commitment to modernize all three legs of the U.S. nuclear triad as part of strategic arms treaty negotiations. The formal process to develop a replacement for the aging Minuteman III missile began in 2016. After an initial competitive phase, one of the primary contenders withdrew from the bidding process, leading to a sole-source development contract being awarded in 2020. The system received its official LGM-35A Sentinel designation in April 2022. The program has since encountered significant cost growth and schedule delays, prompting a critical review which ultimately certified the missile as essential to national security, allowing development to proceed under revised cost estimates.

Powered by a three-stage solid-fuel rocket motor, the Sentinel is a silo-launched intercontinental ballistic missile designed for strategic nuclear deterrence. It will be armed with thermonuclear warheads, initially fielding the W87 mod 0 before transitioning to the more advanced W87 mod 1. The warheads are capable of both ground-burst and air-burst detonation modes. While the U.S. Air Force intends to deploy each missile with a single warhead, the system's high throw-weight offers inherent flexibility. This design provides a potential future capability to field multiple independently targetable reentry vehicles (MIRVs) or advanced penetration aids should they be required to overcome future adversary anti-ballistic missile systems.

The LGM-35 Sentinel is set to replace the entire force of 450 Minuteman III missiles, with initial deployment planned to begin in 2030 and a projected service life extending to 2075. The U.S. Air Force plans to maintain a force of 400 operational missiles, which will be supported by a total procurement of 634 units to accommodate development, testing, and attrition. Deployment necessitates a massive infrastructure overhaul, as it was determined that the existing Minuteman III silos cannot be reused. This requires the construction of new silos and the modernization of over 600 facilities spread across approximately 40,000 square miles of existing missile fields in North Dakota, Wyoming, Montana, and Nebraska.