Iran war has cost $38 billion, depleted two-thirds of US missile interceptors, CBO says

The U.S. military has incurred about $38 billion in costs from combat operations against Iran through Aug. 1, while the conflict’s main opportunity cost has been the missile-defense interceptors the Pentagon has expended defending U.S. forces and allies, according to a new Congressional Budget Office analysis released today.

CBO estimates the conflict has consumed between one-half and two-thirds of the U.S. inventory of certain missile-defense interceptors since June 2025, leaving the military with fewer weapons available for a future conflict. Rebuilding those stocks could take at least five years, even if production rates increase, the agency found.

The estimate includes Patriot, Terminal High Altitude Area Defense, or THAAD, Standard Missile-3 and Standard Missile-6 interceptors. CBO said the Pentagon does not disclose how many interceptors it has in its inventory. Instead, analysts compared reported expenditures with the total number of missiles DoD has purchased to estimate how much of the inventory has been used. The estimate applies to the combined inventory of those four interceptor systems.

Those interceptors accounted for $13.1 billion of the $21.7 billion CBO estimates the Pentagon would need to replace in munitions that were expended through Aug. 1. Land-attack cruise missiles accounted for another $7.3 billion, with $1.2 billion for other munitions.

A separate Defense Department inspector general report estimated the cost of the operation at $33.4 billion through June 29.

CBO said the campaign involved large expenditures of munitions during the first few weeks, particularly as U.S. forces defended against Iranian ballistic missile and drone attacks.

The interceptor depletion is particularly significant because the weapons are expensive and produced at relatively low rates. CBO estimates unit costs of roughly $4 million for a Patriot or SM-6, $12 million for a THAAD interceptor and $28 million for a sophisticated SM-3. The agency said the United States has already used significant quantities of these weapons defending Israel and then expended more during Operation Epic Fury.

That figure includes expended munitions, equipment losses, increased flying hours, other operations and higher fuel costs. It does not include costs borne by other federal agencies or military operating costs already included in the federal budget.

The highest costs beyond munitions were $10.4 billion for increased flying hours, $2.7 billion for fuel and $1.9 billion to replace equipment lost in battle. The equipment losses included a THAAD radar destroyed by Iran.

The initial phase of Operation Epic Fury involved about 250 tactical aircraft, including roughly 90 from two carrier strike groups, as well as an amphibious ready group. Those forces were supported by bombers, airlifters, refueling tankers, other Navy vessels and Army air-defense, aviation and artillery units.

CBO said the Pentagon did not respond to its requests for information, so analysts relied on government databases and public reports. The agency cautioned that its estimate is therefore subject to considerable uncertainty.

The administration had requested $87.6 billion in supplemental funding in June, including $67.1 billion for the DoD, with $42.3 billion identified as directly related to the conflict. That portion was about 10% higher than CBO’s estimate.

The cost of the conflict also continues to grow. CBO estimates each additional month of fighting would cost roughly $2 billion to $3 billion if the intensity remains relatively low, with costs potentially higher if operations intensify.

The depleted interceptor stocks could pose a particular problem in a conflict with China, CBO said, because Beijing maintains large numbers of ballistic and cruise missiles.