ICBM Modernization: Air Force Actions Needed to Expeditiously Address Critical Risks to Sentinel Transition
Fast Facts
DOD is replacing the Air Force's Minuteman III missile—which is over 50 years old—with the new Sentinel system. The transition is the most complex project the service has undertaken.
But the Air Force hasn't developed a risk management plan for this transition. A risk management plan would outline how to anticipate, analyze, and solve problems.
Also, the Air Force may need to operate Minuteman III for 25 more years because of Sentinel delays and increasing costs. It needs a plan to address the risks associated with maintaining the aging system. Parts may no longer be available, for example.
Our recommendations address these issues and more.
Air Force Airmen Performing Maintenance on a Minuteman III ICBM at a Colorado launch facility, February 2024
Highlights
What GAO Found
The Air Force has developed planning documents for the transition from Minuteman III to Sentinel but has not developed a risk management plan. The transition was planned to begin in fiscal year 2025, but those plans are on hold while the Department of Defense (DOD) restructures the Sentinel program. The Air Force developed an overarching transition strategy and a site transition plan for F.E. Warren Air Force Base in Wyoming, the first base scheduled to convert to Sentinel. However, the Air Force has not yet developed a transition risk management plan, a leading project planning practice. A detailed risk management plan would help the Air Force establish an organized, methodical way to identify, assess, and respond to the myriad risks, and better position the Air Force for a successful transition from Minuteman III to Sentinel.
While the Air Force has taken some actions to prepare operators, maintainers, and security forces for the transition, the Air Force has not developed a schedule for construction of a Sentinel test facility. The test facility is necessary early in the transition as part of a multistep process to revise policy and instructions that will be needed to prepare security forces for the transition and concurrent operation of Minuteman III and Sentinel.
Air Force Missile Maintainer in a Missile Training Silo in Montana, March 2025
DOD is assessing options to meet strategic deterrent requirements during the transition, but delays require prolonged operation of Minuteman III. Air Force officials are assessing options to potentially operate Minuteman III through 2050. However, prolonged operation presents sustainment risks. Addressing these risks in a transition risk management plan would help ensure the intercontinental ballistic missile (ICBM) system meets requirements during the transition.
This is a public version of a classified report that GAO issued in April 2025. This public version omits some information on plans and capabilities, the Sentinel test facility, and strategic deterrent requirements DOD deemed to be sensitive or classified.
Why GAO Did This Study
The U.S. has operated the land-based Minuteman III ICBM system for over 50 years, well past the original intended service life of 10 years. The system includes more than 600 facilities, including 450 missile silos, across five states. The replacement system, Sentinel, faces critical cost overruns and schedule delays. The Air Force must continue to operate and maintain the aging Minuteman III system to meet U.S. strategic deterrent requirements until Sentinel is fully fielded.
A report accompanying a bill for the National Defense Authorization Act for Fiscal Year 2024 includes a provision for GAO to review the Air Force’s planning for the transition from Minuteman III to Sentinel ICBM. This report addresses the extent to which the Air Force (1) planned for the transition and concurrent operation of Minuteman III to Sentinel, (2) developed plans to prepare operators, maintainers, and security forces for the transition, and (3) developed plans to meet strategic deterrent requirements during the transition. GAO collected and reviewed relevant documents and interviewed DOD and Air Force officials about transition planning efforts.
Recommendations
GAO is making six recommendations to the Air Force including that the service develop a risk management plan for the transition that addresses Minuteman III sustainment risks and other key transition risks, and establish a schedule for completion of the Sentinel test facility. DOD concurred with all six recommendations.
Recommendations for Executive Action
| Agency Affected | Recommendation | Status |
|---|---|---|
| Department of the Air Force | The Secretary of the Air Force should develop a transition risk management plan for the transition from Minuteman III to Sentinel ICBM. The plan should include a transition risk report and a risk register in future Programming Plan updates. (Recommendation 1) |
The Air Force concurred with our recommendation. As of August 2025, according to Air Force officials, the service has started the process of developing a transition risk management plan with a goal to complete the plan in 2026. In its Corrective Action Plan, the Air Force stated that the service established a transition risk management plan working group in June 2025. When we confirm the actions the agency has taken in response to this recommendation, we will provide updated information.
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| Department of the Air Force | The Secretary of the Air Force should establish a detailed, logical, and sequenced schedule for completion of the Physical Security System Test Facility that aligns with Sentinel restructuring plans and reflects scheduling best practices. (Recommendation 2) |
The Air Force concurred with our recommendation in its response to our classified report. Subsequently, the Air Force provided new information about its plans for the test facility. Officials told us that the Air Force plans to explore alternatives to the test facility that would achieve test and evaluation requirements faster and at lower cost. As of July 2026, officials plan to address these alternatives as part of an updated Sentinel Test and Evaluation Master Plan and Live Fire Test and Evaluation Alternative Test Plan. Officials plan to include these in the package of documents to support the Sentinel Milestone B decision scheduled for fiscal year 2027. When we confirm the extent to which these alternatives address the intent of our recommendation, we will provide updated information.
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| Department of the Air Force | The Secretary of the Air Force should complete an assessment of personnel needs for the transition, including potential Reserve Component support for the transition. (Recommendation 3) |
The Air Force concurred with our recommendation. In its initial Corrective Action Plan, officials stated the service plans to develop a new Manpower Estimate Report as part of the Sentinel restructuring that will include an assessment of personnel needs for the transition. The Manpower Estimate Report is scheduled for completion in September 2026. In the interim, Air Force Global Strike Command and Air Force Reserve Command signed a record of decision in February 2025 to create a missile operator reserve unit consisting of 35 personnel. The Air Force intends to establish this unit in fiscal year 2027 to mitigate transition risk, according to officials. The Air Force is also exploring other reserve integration opportunities in specialized mission areas such as cyber operations to help alleviate personnel needs during the transition. When we confirm the extent to which these actions are complete and address the intent of our recommendation, we will provide updated information.
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| Department of the Air Force | The Secretary of the Air Force should expeditiously develop a post-2030 Minuteman III operational test launch plan that is aligned with a Sentinel fielding plan and coordinated with the Department of Energy. (Recommendation 4) |
The Air Force concurred with our recommendation. As of July 2026, Air Force Global Strike Command is actively working on a post-2030 Minuteman III operational test launch plan with the Air Force Nuclear Weapons Center and the Department of Energy. When we confirm actions the agency has taken in response to this recommendation, we will provide updated information.
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| Department of the Air Force | The Secretary of the Air Force should specifically address Minuteman III sustainment risks in the overall transition risk management plan. (Recommendation 5) |
The Air Force concurred with our recommendation. In its Corrective Action Plan, officials stated that Air Force Global Strike Command and the Air Force Nuclear Weapon Center continuously track Minuteman III sustainment risks. As of June 2025, officials stated that as the service builds the transition risk management plan, they plan to track Minuteman III sustainment risks in a risk report and risk registers. When we confirm the actions the agency has taken in response to this recommendation, we will provide updated information.
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| Department of the Air Force | The Secretary of the Air Force should specifically address the personnel and materiel implications of a decision to re-MIRV ICBMs as part of the overall transition risk management plan. (Recommendation 6) |
The Air Force concurred with our recommendation. In its Corrective Action Plan, the Air Force stated that the service intends to address the implications of a decision to re-MIRV ICBMs as part its transition risk management plan estimated for completion in 2026. When we confirm the actions the agency has taken in response to this recommendation, we will provide updated information.
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