CBO Estimates Golden Dome at $1.2 Trillion, Space-Based Interceptors Biggest Cost

The Congressional Budget Office issued an updated estimate today of the cost of President Trump’s Golden Dome missile defense system. Lacking detailed data from the Administration, CBO based its analysis on the capabilities called for in Trump’s January 2025 Executive Order and concluded the total cost over 20 years is $1.2 trillion, about twice its estimate last year, with the bulk of it for Space-Based Interceptors.

Trump issued the Iron Dome for America Executive Order on January 27, 2025, seven days after his second term began. He soon renamed it Golden Dome in part to distinguish it from Israel’s Iron Dome system which has more limited capabilities.

Trump appointed Gen. Michael Guetlein to lead the project and in an Oval Office meeting on May 20, 2025, said it would cost $175 billion and be completed in three years, before he leaves office.

By then CBO had estimated the cost at $524 billion based on information available at the time.

Guetlein has since raised his estimate to $185 billion, but it is widely viewed as far too low.

Today’s CBO report reached the $1.2 trillion (in 2026 dollars) estimate based on its assesment of the cost to develop, deploy and operate for 20 years the National Missile Defense (NMD) components spelled out in the Executive Order. Just over $1 trillion is for acquisition and the remainder for annual operating costs.

The lion’s share of the cost — 70 percent of acquisition and 60 percent overall — is for a constellation of Space-Based Interceptors that would be needed to “engage” 10 Intercontinental Ballistic Missiles (ICBMs) launched almost simultaneously during their boost phase, the first 3-5 minutes of flight. CBO estimated a constellation of 7,800 satellites in near-polar orbit would be needed at a cost of about $720 billion to develop, deploy and maintain for 20 years, plus $1 billion annually to operate. That assumes $22 million per satellite for the initial 7,800, plus nearly 1,600 each year thereafter since they have a 5-year service life.

The number of satellites and the service-life limitation is because they need to be in low Earth orbit at an altitude of 300-500 kilometers, where atmospheric drag is high, to be close enough to their targets within those 3-5 minutes, according to CBO.

CBO noted the substantial difference between their estimate and the Trump Administration’s, offering that either the Golden Dome architecture is much more limited than what is required in the Executive Order or funding might be coming though other parts of the defense budget. The time frames also are different. Limited information from the Administration makes a comparison difficult, CBO conceded, and “many variations are possible.”

DOD is requesting $17.9 billion for Golden Dome in FY2027 according to the Comptroller’s Budget Overview book. OMB shows $398 million in the base budget request that goes through the “discretionary” appropriations process, plus $17.1 billion in “mandatory”spending, a total of $17.5 billion. The reason for the discrepancy with the Comptroller’s figure isn’t obvious.

Mandatory spending in this case means through the reconciliation process, which is separate from appropriations. It’s a unique legislative process that allows the Senate to approve spending on a partisan basis, avoiding the Senate filibuster. Last summer’s One, Big Beautiful Bill Act (OBBBA), is the most recently passed reconciliation bill. Another is in development right now to fund ICE and CBP. A third would be needed for the majority of Golden Dome funding plus a number of other Administration priorities.