Proposed Action

In March 2023, the Department of the Air Force (DAF) completed a comprehensive Environmental Impact Statement (EIS) analyzing the full scope of environmental impacts associated with:

• Recapitalization of the U.S. land-based Minuteman III (MMIII) intercontinental ballistic missile (ICBM) fleet with Sentinel;

• Sequential deployment: F.E. Warren Air Force Base (AFB), WY, Malmstrom AFB, MT, then Minot AFB, ND;

• Modernization, replacement, or reuse of missile alert facilities (MAFs) sites, launch facilities (LFs) sites, and supporting infrastructure; and

• Decommissioning and disposing of MMIII missiles and associated equipment

The Elements Analyzed in the 2023 EIS Included:

• Infrastructure upgrades and new construction at MAFs, LFs, communication towers, utility corridors, and support installations;

• Temporary workforce hubs and laydown areas for each missile field; and

• Dismantlement and removal of MMIII components including missiles and support equipment.

In May 2023, the DAF signed the Record of Decision (ROD), which included more than 380 mitigation measures that address the impacts of the Proposed Action.

Since publication of the 2023 ROD, the DAF determined the original approach to recapitalizing all existing MMIII infrastructure could not be carried forward as key Sentinel Program milestones were no longer achievable based on cost and schedule risks associated with converting existing LF sites to Launch Silo (LS) sites. After detailed engineering reviews, the DAF restructured its basing approach from legacy facility reutilization to modernized, new-build LS and Launch Center (LC) sites. These substantial changes are being addressed in a Sentinel Supplemental Environmental Impact Statement (SEIS).

The SEIS will analyze potential effects on the human and natural environments resulting from changes to the Sentinel Program since the 2023 EIS. The Proposed Action would support construction and transition to Sentinel facilities at F.E. Warren, Malmstrom, and Minot AFBs. The DAF would use a disciplined siting hierarchy with flexibility to address site constraints, construction requirements, and operational needs. These changes reflect refinements in missile system design, finalized engineering requirements, and advancements in deployment planning. Key updates being evaluated across the three AFBs and their missile wings include:

• The redesign, repurpose, or relocation of workforce hubs, as required.

• Closure of MMIII LF sites in place using appropriate methods, including backfilling, demolition, dismantlement, burial, and/or implosion.

• Acquisition of up to 12 acres per LS site and up to 16 acres per LC site within missile fields to provide operational flexibility.

• Maintenance of an operational configuration of 150 LS sites at each missile field throughout construction/transition to new facilities.

• Reutilization of MAF sites for LCs where feasible, with site footprint up to 16 acres.

• In-field MH-139 (Grey Wolf) helicopter refueling and rearming capability at selected LC sites.

• Construction of additional on-base facilities

These changes are necessary to support full Sentinel System deployment while maintaining continuity of operations and ensuring consistency with updated siting, security, and mission requirements. 

F. E. Warren AFB

• Acquisition of land and construction of up to 30 new LS sites.

• Reutilization, procurement, and conversion of existing LF sites to LC sites

Malmstrom AFB

• Acquisition of land and construction of up to 30 new LS sites.

• Reutilization of former 564th Missile Squadron geographic sites for up to 60 new LS sites.

• Construction of a purpose-built Operations Group Facility.

• Establishment of temporary laydown areas to support construction in the 564th area. 

• Positioning of laydown areas to improve construction efficiency, schedule, and cost.

Minot AFB

• Acquisition of land (west and east of the existing missile field) for up to 60 new LS sites.

• Construction of new LCs sites in previously undeveloped areas.