WASHINGTON, D.C. — The Defense Department's Golden Dome Office has repeatedly refused requests from the Congressional Budget Office for a briefing on its plans. This refusal has created a dispute over cost estimates and program scope for the proposed missile defense system.

David Mosher, head of the CBO National Security Directorate, told the Brookings Institution that his agency has been unable to obtain information from the office. "We have, to date, not been able to talk to the Golden Dome Office," Mosher said.

Mosher explained that the lack of access prevents the CBO from assessing the specific technologies under development. "We've asked them for briefings, and we have not gotten any. They've not been willing to do so. So, I know nothing about what they're actually building."

The Congressional Budget Office estimated the cost of the missile shield at $1.2 trillion in May 2026. The agency's review found that a notional national missile defense system could cost up to $1.2 trillion to develop, deploy, and operate for two decades.

The Pentagon criticized the Congressional Budget Office's cost estimate as being based on inaccurate information. Space Force Gen. Michael Guetlein stated that the estimates rely on old technology and incorrect assumptions about the planned architecture.

"Those cost estimates are not estimating what we are building," Gen. Guetlein said in a podcast interview. Guetlein had previously stated in April that costs had risen to $185 billion to deploy over the next decade.

Mosher noted that the CBO's tasking was to look at implementing the White House's original executive order, while the Golden Dome office is projecting current spending plans. "And remember, we were not costing what the Golden Dome Office is building," he added. "We were trying to estimate what the cost of the executive order."

The administration's fiscal 2027 budget request includes $17.5 billion for Golden Dome. Approximately $400 million of the fiscal 2027 Golden Dome funding is in the Pentagon's base budget, with the rest in reconciliation funding.

Timeline

President Donald Trump issued an executive order in January 2025 calling for nationwide defense against ballistic, hypersonic, advanced cruise missiles, and other next-generation aerial attacks. The program was renamed Golden Dome for America in February 2025 to avoid confusion with Israel's Iron Dome missile defense system.

Gen. he stated in April that costs had risen to $185 billion to deploy over the next decade. In May 2026, the Congressional Budget Office estimated the cost of the missile shield at $1.2 trillion.

The Congressional Budget Office report notes that FY27 budget documents show an average cost of about $15 billion per year for the rest of Golden Dome's five-year spending plan. The Congressional Budget Office report concludes that the Department of Defense's stated cost appears to cover a shorter time frame than the CBO's analysis and may reflect a different scope of activities and budget categories. "Those cost estimates are not estimating what we are building," Gen. he told the annual Army Space and Missile Defense Symposium in Huntsville, Ala. On Aug. 11.

Why It Matters

The dispute shows a divergence between congressional oversight capabilities and Defense Department planning for major acquisition programs. The $1.2 trillion estimate covers a twenty-year period for development, deployment, and operation, while the Pentagon's figures focus on a shorter timeframe and different budget categories. This discrepancy affects how lawmakers evaluate the fiscal impact of the Golden Dome initiative within the federal budget.

Access to detailed program information remains a central issue, as the CBO relies on public documents and executive orders when direct briefings are denied. The outcome of this disagreement will influence future funding allocations and the scope of the missile defense architecture. Members of Congress continue to seek answers regarding the specific technologies and costs associated with the project.