GAO: Pentagon obligated $2.64 billion for southern border operations through March 31, 2026

The Pentagon obligated $2.64 billion for southern border operations from the start of fiscal 2025 through March 31, 2026, assembling the money through several different funding channels, according to a new report from the Government Accountability Office, the investigative arm of Congress.

In its report, GAO-26-108437, published Monday, GAO said the Defense Department “used multiple strategies to fund support for southern border operations since the start of fiscal year 2025.” Those included $1.74 billion realigned from fiscal 2025 appropriations, $608 million transferred from or through the department’s drug interdiction and counter-drug account, and $300 million financed through military-construction authorities for border barrier projects. GAO also said the Pentagon later began obligating money from a separate $1 billion appropriation provided in Public Law 119-21, enacted July 4, 2025, and began providing some fiscal 2026 support to the Department of Homeland Security that is eligible for reimbursement. Of the $2.64 billion total reported through March 31, 2026, $305 million was eligible for DHS reimbursement.

The accounting matters because it is the clearest public breakdown yet of how much the mission has cost and how the Pentagon paid for it. It also shows that the department did not rely on a single, dedicated funding stream at the outset. Instead, it shifted money from other Pentagon priorities, most notably facilities upkeep and modernization.

GAO said 73% of the $1.74 billion that DOD realigned in fiscal 2025 came from the Facilities Sustainment, Restoration, and Modernization program, a broad pot of money used to maintain and repair military infrastructure. That makes the report one of the strongest public indications so far of the trade-offs inside the defense budget as the border mission expanded.

The largest spending category was border security itself, at $1.45 billion. GAO also reported $387 million for National Defense Areas — border lands administered by DOD as part of the mission — $366 million for detention operations in the continental United States, and $275 million for permanent border barrier work.

The report includes several examples of how the funding was assembled. On April 25, 2025, DOD transferred $161 million from the counter-drug account to the Army’s operations and maintenance account. Less than a month later, on May 19, 2025, DOD transferred $447 million from the Navy Defense Working Capital Fund through the counter-drug account; GAO said $442 million of that was for Immigration and Customs Enforcement detention operations and $5 million was for military department detention-related expenses at Naval Station Guantanamo Bay.

For construction, GAO said DOD used existing military construction appropriations and specific statutory authorities for barrier projects in Arizona and New Mexico. The department used 10 U.S.C. Section 2803 for a border barrier project at Barry M. Goldwater Range and 10 U.S.C. Section 2808 for projects at the New Mexico annex of Fort Huachuca. GAO reported that $338 million had been obligated from the military construction appropriation category, including $191 million for Barry M. Goldwater Range and $83 million for the New Mexico barrier project.

The backdrop for the spending was a January 2025 presidential declaration of a national emergency at the southern border, which directed DOD to assist DHS in obtaining what the order called “complete operational control” of the border. GAO said the Pentagon then deployed thousands of service members in support of the mission.

The later $1 billion appropriation in Public Law 119-21 gave DOD a dedicated source of money for border-related military deployments, operations, National Defense Areas and temporary detention on military installations. But GAO’s report shows that before and alongside that appropriation, the department relied on a patchwork of internal shifts, transfers and construction authorities.

To track the costs, DOD and the military services set up a reporting process using Advana, the department’s enterprise management system. GAO said an April 25, 2025, memo from the Office of the Under Secretary of Defense comptroller made Advana the authoritative source for the reports, though DOD is still working to finalize standard operating procedures for managing and tracking southern border costs.

GAO said it provided a draft of the report to DOD. The department did not provide official comments, but it did submit technical comments that GAO incorporated as appropriate. GAO also said it expects to issue a separate legal decision later in 2026 on whether DOD complied with statutory requirements when it used military-construction funds for the Barry M. Goldwater Range barrier project.