Ground-Based Strategic Deterrent

The Ground-Based Strategic Deterrent (GBSD) is the United States Air Force acquisition program developing a next-generation intercontinental ballistic missile (ICBM) system to replace the Minuteman III, which has been in service since 1970. In April 2022 the program was officially designated the LGM-35A Sentinel. Northrop Grumman was awarded the engineering and manufacturing development contract in September 2020 after Boeing withdrew from the competition, citing concerns over solid rocket motor supply.

The program covers more than just the missile itself. It is intended to modernize the entire land leg of the U.S. nuclear triad, including launch facilities, launch control centers, command-and-control systems, and supporting infrastructure across the missile fields in Wyoming, Montana, North Dakota, Nebraska, and Colorado. The planned force structure is roughly 400 deployed missiles, consistent with limits under the New START Treaty (2010).

GBSD/Sentinel has become a focal point of debate over nuclear modernization costs. In January 2024 the Pentagon notified Congress of a critical Nunn-McCurdy cost breach, with per-unit costs rising substantially above baseline. Following a review, the Department of Defense in July 2024 certified the program to continue but ordered restructuring, with deployment timelines pushed beyond original mid-2030s targets.

Critics, including some arms-control analysts and members of Congress, argue that the land-based leg is destabilizing because silos are fixed targets that may invite a "use-it-or-lose-it" posture. Proponents counter that ICBMs complicate adversary targeting by forcing an attacker to expend hundreds of warheads against the homeland, and that they provide the most responsive and survivable command link of the three legs. The program is central to broader debates over U.S. deterrence strategy vis-à-vis Russia and China.