Missile Defense: The U.S. Department of Defense Faces Support and Coordination Challenges in Guam Defense

Key Chapter Title List

1. Background
2. DOD Has Established Organizations to Manage GDS and Designated Lead Service Responsibilities but Has Not Yet Transferred Service Responsibilities
3. DOD's Plans to Support Future GDS Forces on Guam Are Incomplete
4. Conclusions
5. Recommendations for Executive Action
6. Agency Comments and Our Evaluation
7. Appendix I: Key Organizations and Facilities We Visited for Our Review
8. Appendix II: Potential Impact of GDS on Guam Resources
9. Appendix III: Directed Changes to the GDS Architecture as of January 7, 2025
10. Appendix IV: Comments from the Department of Defense
11. Appendix V: GAO Contact and Staff Acknowledgments
12. Related GAO Products

Document Introduction

This report is the public version of an independent audit conducted by the U.S. Government Accountability Office (GAO) in response to provisions in the Fiscal Year 2024 National Defense Authorization Act, examining how the Department of Defense (DOD) plans to sustain and support the Guam Defense System (GDS). As a U.S. territory and a critical strategic hub in the Indo-Pacific region, Guam's defensive capabilities are essential for maintaining U.S. influence and deterring adversaries. In response to increased Chinese military activities in the Indo-Pacific, DOD is working to develop and deploy an enhanced, integrated air and missile defense system called the Guam Defense System (GDS), building upon the existing Terminal High Altitude Area Defense (THAAD) system to provide persistent, 360-degree defensive capabilities. This report assesses the progress and challenges DOD has faced in establishing the GDS organizational structure and planning for future force support.

The core review of the report revolves around two main objectives: first, to assess whether DOD has established an organizational structure to oversee and sustain GDS; and second, to assess whether DOD has developed support plans for future missile defense forces on Guam. GAO's audit methodology included site visits to relevant military facilities in Guam, Hawaii, and Japan, as well as extensive interviews with senior DOD officials, the military services, the Missile Defense Agency (MDA), and Guam government officials. Furthermore, GAO reviewed DOD policy documents regarding system development, force structure, and internal controls, and conducted comparative analysis with the information obtained.

The audit found that DOD has taken initial steps to establish a GDS management organizational structure, such as setting up a Joint Program Office (JPO) managed by the Army to coordinate Guam missile defense matters and designating lead services for each GDS subsystem responsible for its operation and maintenance. However, key challenges remain. First, DOD lacks a clear strategy outlining when and how the designated lead organizations (services or MDA) will formally assume responsibility for operating and maintaining the relevant subsystems, which could lead to subsequent deployment delays and incomplete planning. Second, the Army has not yet developed a long-term strategy to define its organizational form as the "supported command" within the Joint Region Marianas (JRM) on Guam, which affects the Army's ability to coordinate its own construction priorities and obtain base support services across multiple bases on Guam.

A more serious issue is that DOD has not fully determined the personnel requirements for GDS nor completed the deployment timeline for the relevant forces. Without this critical information, the services cannot effectively plan, fund, and construct the necessary supporting infrastructure for the incoming GDS personnel and their families, including barracks, housing, schools, medical facilities, and commissaries. The report notes that Guam's existing support facilities are already under capacity pressure, and the relocation of Marines from Okinawa will further strain resources such as housing, education, and healthcare. An increase in GDS personnel without adequate planning will significantly exacerbate these infrastructure challenges, affecting force readiness and personnel morale.

Based on the above findings, GAO makes three recommendations to the Secretary of Defense in this public version of the report: first, that the Under Secretary of Defense for Acquisition and Sustainment coordinate the development of a strategy, timeline, and plan for transferring GDS responsibilities; second, that the Secretary of the Army coordinate the development of a long-term organizational strategy for the Army as the supported command within JRM; and third, that the Secretaries of the military services determine GDS personnel requirements and develop a deployment timeline. DOD concurred with all recommendations. Although this is a public version, it is abridged from a classified report issued in February 2025, omitting one objective, one recommendation, and some content designated as "classified" or "controlled unclassified information." It aims to provide professional readers with an authoritative, in-depth analysis of the internal governance and logistical planning challenges the United States faces when deploying complex defense systems in critical forward areas.