Guam is a small but strategically important U.S. island in the western Pacific. The Congressional Research Service (CRS) describes it as approximately 30 miles long and more than 3,300 nautical miles west of Hawaii. It is home to about 170,000 U.S. citizens, while the U.S. Department of Defense (DOD) owns about 25% of the island’s land. These geographic and demographic facts help explain why military personnel, bases, infrastructure, and construction spending are central to Guam’s civic and economic landscape.
Contents
- Guam’s military footprint
- Personnel by service
- Major bases and naval forces
- Air power, fuel, and missile defense
- Guam Defense System timeline
- Defense planning personnel and funding
Guam’s military footprint
CRS reports that DOD maintains about 6,400 active-duty servicemembers on Guam. Its broader count is 11,616 total DOD personnel, including active-duty, reserve, and civilian employees. The difference between these figures reflects the wider workforce connected to Guam’s defense presence rather than active-duty members alone.
CRS also identified at least 46 military units permanently based on Guam. Joint Region Marianas, the organization associated with the island’s joint military presence, was established in 2009. Together, the unit count and the total personnel count show that Guam’s military role is distributed across multiple services and missions rather than centered on a single installation.
The island’s physical scale makes the land-use figure especially significant. DOD ownership of about one-quarter of Guam’s land places military facilities, training areas, housing, utilities, airfields, ports, and related infrastructure within a substantial share of the island’s geography. The CRS measurements describe Guam’s size and DOD’s landholding, but they do not provide a current breakdown of military-owned acreage by installation.
Personnel by service
The CRS personnel table reports 11,616 DOD personnel on Guam. The largest service totals are the Navy and the Air Force/Space Force, followed by the Army and Marine Corps. The table below retains the source’s categories and counts.
| Service or component | Total personnel | Active-duty | Reserve | Civilian |
|---|---|---|---|---|
| Army | 2,049 | 207 | 1,657 | 185 |
| Air Force/Space Force | 3,333 | 2,250 | 648 | 435 |
| Navy | 5,352 | 3,825 | 177 | 1,350 |
| Marine Corps | 144 | 135 | Not provided | 9 |
| Other DOD components | 738 | Not provided | Not provided | 738 |
The Navy’s 5,352 personnel represent the largest service total in the CRS data. That total includes 3,825 active-duty personnel, 177 reservists, and 1,350 civilian employees. The Air Force/Space Force total is 3,333, including 2,250 active-duty personnel, 648 reserve personnel, and 435 civilians.
The Army has 2,049 personnel on Guam. Its reported composition is notably reserve-heavy: 207 active-component personnel, 1,657 reserve-component personnel, and 185 civilian employees. The Marine Corps has 144 personnel, including 135 active-duty members and 9 civilians. Other DOD components account for 738 civilian personnel.
These figures should be read as the CRS-reported personnel snapshot associated with its source material. They are not a forecast of future staffing, and the supplied research does not identify a measurement date for every service total. The categories also should not be used to infer unreported active-duty or reserve counts for Marine Corps or other DOD components.
Major bases and naval forces
Naval Base Guam is located in Apra Harbor. CRS states that the harbor can accommodate the largest Navy warships, including aircraft carriers. The port’s capacity is therefore relevant both to Guam’s local military footprint and to the island’s role in supporting larger naval operations in the western Pacific.
Polaris Point Submarine Base is homeport to five Los Angeles-class nuclear-powered fast attack submarines. CRS reports that the Navy increased the number of attack submarines homeported at Guam to five in 2022, up from three or four at various times during the prior decade. Two Navy tender ships are also based in Guam.
The submarine count is a point-in-time operational statistic tied specifically to the 2022 increase described by CRS. It does not mean that every Navy vessel discussed in the source is present at the same time, nor does it quantify temporary visits by ships or aircraft carriers.
CRS also notes a limitation in Guam’s naval maintenance infrastructure: the Navy’s ship maintenance capabilities were reduced after a floating drydock was removed in 2016. The supplied facts do not quantify the resulting maintenance capacity or identify a replacement drydock. The statistic is therefore best understood as a dated change in capability, not as a current measure of repair throughput.
Air power, fuel, and missile defense
Andersen Air Force Base has more fuel and munitions storage than any other Air Force base, according to CRS. Its upgraded pipeline system can provide more than 4 million gallons of jet fuel per day. That capacity is enough to supply more than 100 tanker aircraft sorties, giving the base a substantial logistics role even though it does not have permanent Air Force aircraft assigned to it.
The 36th Wing is Andersen’s host unit. Permanent air assets at the base include Navy MQ-4 and RQ-4 Global Hawks and Navy MH-60S Seahawks helicopters. Andersen also hosts rotational tanker task forces composed of KC-135 units and rotational bomber task forces composed of B-1 and B-52 units.
The distinction between permanent and rotational assets matters when interpreting Guam military statistics. The CRS data identifies the 36th Wing as the host unit and lists permanent Navy assets, but it does not give a fixed aircraft total for the rotational tanker and bomber task forces. A rotation describes a recurring or temporary deployment pattern, not a permanently assigned fleet.
The Army deployed a Terminal High Altitude Area Defense (THAAD) battery to Guam in 2013. CRS reports that the battery is manned by about 100 soldiers and consists of six launchers. Each launcher carries eight interceptor missiles. Separately, the Government Accountability Office (GAO) states that DOD currently defends Guam with a battery of six missile launchers and one radar.
The two source descriptions concern Guam’s missile-defense posture but should not be merged into unsupported additional totals. The THAAD figures describe the battery’s reported manpower and launcher configuration, while GAO’s description identifies the current defense arrangement in its report.
Guam Defense System timeline
GAO-25-108187 states that the planned Guam Defense System (GDS) is intended to provide a persistent 360-degree defense of Guam. DOD plans to distribute GDS elements across 16 sites on the island. The first GDS deployment is planned for fiscal year 2027, and the final elements are planned to arrive by fiscal year 2032.
CRS R47643 describes an earlier projected schedule for the future Guam missile-defense architecture: initial capability was projected for 2024, with enhanced capability projected for 2029. The architecture is intended to be controlled by a Joint Command Center and planned to use three separate service-related missile-defense programs at multiple sites across Guam.
| Planning measure | Reported figure or date | Source |
|---|---|---|
| Planned GDS sites | 16 | GAO-25-108187 |
| First GDS deployment | Fiscal year 2027 | GAO-25-108187 |
| Final GDS elements | Fiscal year 2032 | GAO-25-108187 |
| Earlier projected initial capability | 2024 | CRS R47643 |
| Earlier projected enhanced capability | 2029 | CRS R47643 |
| Planned missile-defense programs | 3 | CRS R47643 |
The dates are plans or projections, not completed milestones. The GAO schedule and the earlier CRS projections should be kept distinct because they describe different planning statements and timeframes. In particular, a projected 2024 initial capability does not establish that every element of the later 16-site GDS had arrived by that year.
Defense planning personnel and funding
GAO-25-108187 reports that, as of September 2024, the Army’s Joint Program Office had 6 military personnel, 1 civilian, and 4 contractor personnel. The same source says the Army had proposed 129 personnel for the office: 12 military, 89 civilian, and 28 contractor personnel. The reported staffing level and the proposed staffing level are separate measurements; the proposal is not evidence that all 129 positions had been filled.
CRS reports that Missile Defense Agency (MDA) funding for the Defense of Guam program totaled $2,740.9 million across fiscal years 2022 through 2028. Within that total, MDA research, development, test, and evaluation funding totaled $1,935.8 million; procurement funding totaled $367.1 million; and military construction (MILCON) funding totaled $438.0 million. CRS also reports $567.2 million in MDA funding for the Defense of Guam program in fiscal year 2024.
| Funding measure | Amount | Period |
|---|---|---|
| MDA Defense of Guam total | $2,740.9 million | FY2022–FY2028 |
| MDA RDT&E | $1,935.8 million | FY2022–FY2028 |
| MDA procurement | $367.1 million | FY2022–FY2028 |
| MDA MILCON | $438.0 million | FY2022–FY2028 |
| MDA Defense of Guam funding | $567.2 million | FY2024 |
Beyond the MDA program, CRS reports that Congress appropriated more than $3.4 billion for MILCON projects on Guam between fiscal years 2015 and 2023. DOD planned an additional $7.3 billion in Guam MILCON spending for fiscal years 2024 through 2028. Defense.gov separately stated in December 2021 that DOD planned to spend about $11 billion on military construction projects on Guam over the next five years.
The three construction figures use different periods and descriptions. The more than $3.4 billion figure is an appropriation total for FY2015–FY2023. The $7.3 billion figure is a DOD plan for FY2024–FY2028, while the approximately $11 billion statement was made by Defense.gov in December 2021 and refers to a five-year plan. They should not be added together or treated as completed spending without additional source detail.