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1 [1] (March 4, 2026)

handle is hein.crs/govetrg0001 and id is 1 raw text is: Congressional Research Service intorming 11w legislative debate since 1914 0 Updated March 4, 2026 Defense Primer: LGM-35A Sentinel Intercontinental Ballistic Missile The LGM-35A Sentinel is an intercontinental ballistic missile (ICBM) system that is expected to replace the Minuteman III (MMIII) ICBM in the U.S. nuclear force structure. MMIII has served as the ground-based leg of the U.S. nuclear triad-land-based ICBMs, submarine- launched ballistic missiles, and nuclear-capable bombers- since 1970. The Department of Defense (DOD), which is using a secondary Department of War designation, under Executive Order 14347 dated September 5, 2025, requested $4.1 billion for Sentinel research, development, test, and evaluation (RDT&E) in FY2026. This request assumed $1.5 billion from FY2025 reconciliation legislation (P.L. 119-21), commonly referred to as the One Big Beautiful Bill Act. The FY2025 reconciliation legislation included $2.5 billion for Sentinel risk reduction activities. The FY2026 budget request for the Department of Energy's National Nuclear Security Administration (NNSA) included $649 million for the W87-1 nuclear warhead for the Sentinel. The FY2026 National Defense Authorization Act (NDAA P.L. 119-60) authorized $3.8 billion for Sentinel RDT&E and $649 million for the W87-1 warhead. WhatIs an ICBM? A U.S. ICBM can reach targets around the globe in approximately 30 minutes after launch. During the first three minutes, three solid fuel rocket motors power the missile's flight. After the powered portion of flight, the missile follows a parabolic trajectory toward its target. The missile releases its warhead during the mid-course portion of its flight, and the warhead continues to the target. Once the President authorizes the launch of any U.S. ICBM, the missile cannot be recalled or destroyed in flight. The same is true for nuclear missiles launched from U.S. submarines. In contrast, U.S. bombers can return to their bases, without releasing their weapons, although their weapons also cannot be recalled after their release. The United States began deploying nuclear-armed ICBMs in 1959, and has maintained these systems on alert, or able to launch promptly, since that time. The Air Force deployed the Atlas between 1959 and 1965, the Minuteman beginning in the 1960s, and the Peacekeeper (or MX) between 1987 and 2005. The Air Force bases its ICBMs in hardened concrete silos, or launch facilities, located in North Dakota, Montana, Wyoming, Colorado, and Nebraska. The United States has periodically considered alternative ICBM basing concepts to ensure survivability. The T,ranstion from MInuteman The MMIII, which is currently deployed in a single- warhead configuration, but could carry up to three warheads, entered the force in 1970. The Air Force has replaced and updated many of the component systems on the missile-a process known as life-extension-several times over the past 50 years. The Air Force has stated that some of these components may face reliability concerns as they reach the end of their intended lifespans. After conducting an Analysis of Alternatives in 2014, the Air Force decided to replace MMIII with a new missile system (originally Ground Based Strategic Deterrent) that would serve through 2075. The Air Force argued that, when compared with a life-extended MMIII, the new ICBM would meet current and expected threats, maintain the industrial base, produce a modular weapon system, and reduce life cycle cost. The Air Force and Northrop Grumman, the Sentinel's lead defense contractor, planned for the Sentinel to begin replacing MMIII in 2029. Program Status The Air Force plans to procure 634 Sentinel missiles, plus an additional 25 missiles to support development and testing, to enable the deployment of 400 missiles. The Air Force also originally planned to modernize 450 silos and over 600 facilities (see Figure 1). Figure I. Sentinel Deployment and Support Locations EOiState Boundary 200 MILES Launch Facility (LF) t Missile Alert Facility Source: Air Force Global Strike Command, 2023. In January 2024, the Air Force informed Congress that the Sentinel program exceeded its initial cost projections, positing at least a 37% increase (from $118 million initial