Ground Based Strategic Deterrent

The Ground Based Strategic Deterrent (GBSD) program, now designated as the LGM-35A Sentinel, is a major Air Force initiative aimed at modernizing the United States' land-based intercontinental ballistic missile (ICBM) capability. The primary goal of this program is to replace the aging Minuteman III (MM III) ICBM weapon system with a new, fully integrated deterrent that ensures the continued safety, security, reliability, and effectiveness of the nation's nuclear triad. The GBSD program is managed by the Air Force and falls under the Missile Procurement, Air Force appropriation, specifically within the Ballistic Missiles budget activity and subactivity.

The objectives of the LGM-35A Sentinel program are multifaceted. The program seeks to address key capability gaps and vulnerabilities identified in various assessments and documentation, including the Capabilities Based Assessment, Capabilities Development Document, and Analysis of Alternatives for the Sentinel system. By doing so, the program aims to mitigate the risks associated with MM III component age-out and attrition, ensuring that the ground-based leg of the nuclear deterrent remains viable for decades to come. The Sentinel system is designed to lower lifecycle costs and enhance operational effectiveness through improved system integration and technical maturation.

In terms of procurement and research, the LGM-35A Sentinel program encompasses the development of new aerospace vehicle equipment (AVE), which includes a three-stage solid rocket booster, a post-boost propulsion subsystem, and advanced guidance, navigation, and control (GN&C) components. The AVE is engineered to provide improved reliability and performance over the legacy MM III system. Additionally, the program covers the development of support equipment, flight test hardware, infrastructure, and training systems, all of which are essential for the successful deployment and sustainment of the new ICBM system.

The program also includes significant risk mitigation activities related to the transition from MM III to the LGM-35A Sentinel. This involves nuclear surety certification, system vulnerability assessments, and the refinement of requirements and technical specifications in collaboration with stakeholders. The Program Office is tasked with updating program requirements, quantities, and milestones to align with the outcomes of ongoing reassessments and refinements, particularly in light of the recent Nunn-McCurdy recertification and the rescinding of the 2020 Milestone B decision.

During the Engineering and Manufacturing Development (EMD) phase, which has now been rescinded, the program executed several critical activities. These included government system engineering, analytics, test capability development, air vehicle equipment development, command and launch systems development, infrastructure and deployment development, support systems development, and weapon system integration. Although the program has reverted to a pre-Milestone B posture, many of these activities continue to be performed to ensure technical progress and readiness for future milestones.

Funding for the Ground Based Strategic Deterrent line item in FY2026 is limited, with no new procurement requested for that year. Previous years included advance procurement to support ongoing development and risk mitigation efforts. The resource summary indicates that the bulk of recent funding has supported recurring hardware costs and advance procurement, with future event schedules and milestone dates subject to revision based on acquisition strategy updates.