"The system would provide significantly expanded defensive capabilities but would not be impenetrable, particularly against large-scale attacks from peer adversaries," the Congressional Budget Office said in an emailed statement.
CBO estimates Golden Dome at $1.2 trillion
Congressional researchers have concluded that the Golden Dome missile-defense program would cost roughly $1.2 trillion to build out — far more than White House figures and about double the CBO’s own earlier estimate tied to the program’s initial executive order. That $1.2 trillion figure was produced at the request of Sen. Jeff Merkley, D-Oregon, and the CBO cautioned that its number is higher than publicly cited administration figures “which may reflect differences in scope, time frame, and assumptions.”
Space-based interceptors are the single largest cost — $730 billion for capacity to defeat about 10 missiles
The CBO found that the bulk of the program’s cost — about $730 billion — would be spent on space-based interceptors, and that sum would buy enough interceptors to destroy roughly 10 incoming ballistic missiles. The CBO and outside analysts identify space interceptors as the most expensive component of Golden Dome, and the agency’s statement underscores a central constraint: even an expansive buildout “would not be impenetrable,” especially versus large-scale peer threats. The report also notes that physics — the realities of orbital mechanics and coverage — would require tens or hundreds of thousands of satellites to field a shield capable of stopping any number of missiles from anywhere.
Administration budgets, reconciliation funds, and competing estimates
The CBO’s $1.2 trillion estimate sits in stark contrast with multiple figures the administration and its advisers have used. President Trump initially promised a $175 billion price tag; the CBO’s new estimate is “nearly seven times larger” than that pledge. The administration has also placed $79 billion in a Golden Dome for America account over the next five years, a sum the CBO says falls far short. Defense analysts cited in the CBO release also reference an administration figure of $185 billion, which Todd Harrison of the American Enterprise Institute has said “won’t buy anywhere close” to the program described in the executive order.
To finance Golden Dome, the administration has relied heavily on funds outside the Pentagon’s annual baseline. Last year the Pentagon netted $24 billion in reconciliation funds for the program. For the 2027 defense budget, the administration requested more than $17 billion in reconciliation funds and just $400 million from the annual Pentagon budget. According to AEI data cited in the CBO context, the Pentagon plans to request an estimated $14.7 billion in reconciliation funding in 2028, rising to $16 billion by 2031 — amounts that, the CBO’s estimate suggests, would still be a fraction of the $1.2 trillion total.
How Sen. Jeff Merkley, Gen. Michael Guetlein, and Todd Harrison are responding
- Sen. Jeff Merkley: Requested the CBO analysis that produced the $1.2 trillion estimate, placing the congressional oversight spotlight on program cost and scope.
- Space Force Gen. Michael Guetlein (program leader): Told lawmakers he is “focused on staying within the budget” and warned, “If we cannot do it affordabl[ly], we will not go into production” on boost-phase space-based interceptors — a direct acknowledgement that affordability could halt the program’s most ambitious components.
- Todd Harrison, AEI defense budget analyst and space expert: Published a September projection that roughly $1 trillion over two decades could buy a suite of capabilities — a limited number of boost-phase and midcourse intercepts, nearly 150 missile-warning and tracking satellites, multiple ground battalions and batteries, and other systems — and argued publicly that “the administration is not actually building what the executive order described” if it insists on much lower budget figures. Harrison warned that prototyping space-based interceptors will not solve their fundamental scalability limits and urged Congress to prioritize more scalable homeland defenses.
Implications for Congress, the Pentagon, and homeland defenses
The CBO assessment reframes choices for Congress and the Pentagon. If the $1.2 trillion estimate is accepted as the realistic cost of the executive order’s ambitions, lawmakers must decide whether to authorize and appropriate sums far larger than current administration accounts anticipate — or to redefine the program’s scope. The Pentagon, which has already shifted money into Golden Dome via reconciliation, faces a budgeting tradeoff between continuing costly space-based interceptor development and buying more immediately scalable systems. As Harrison put it, money devoted to SBIs “could instead be used to buy more of the ground-based interceptors and drone defenses we are in desperate need of today that do scale with threats.”
The CBO’s number does not declare Golden Dome impossible. It does, however, make the practical question unavoidable: whether Congress and the Pentagon will accept the costs and limits laid out by the budget office, or narrow ambitions to fit current funding plans. That choice will determine whether Golden Dome remains a bold executive vision, a scaled-back set of incremental improvements, or a multi-decade fiscal commitment that reshapes U.S. missile-defense spending.
