U.S. combat operations against Iran have cost about $38 billion through Aug. 1, while the campaign consumed an estimated one-half to two-thirds of the combined U.S. inventory of four major missile-defense interceptor systems since June 2025. Rebuilding those stocks could take at least five years, even if production rates increase, the Congressional Budget Office found in an analysis described by Defense News.

The inventory estimate covers Patriot, Terminal High Altitude Area Defense, or THAAD, Standard Missile-3 and Standard Missile-6 interceptors. The Pentagon does not disclose the number of interceptors it holds, so CBO estimated depletion by comparing reported expenditures with the total number of missiles the Defense Department has purchased. The one-half-to-two-thirds range applies to the combined inventory of those four systems, not to each system individually.

The interceptor use represents the campaign’s main stated opportunity cost: weapons no longer available for a future conflict. CBO estimated that replacing all munitions expended through Aug. 1 would cost $21.7 billion. The four interceptor systems accounted for $13.1 billion of that amount. Land-attack cruise missiles accounted for another $7.3 billion, while other munitions accounted for $1.2 billion.

The figures reflect a campaign that used large quantities of munitions during its first few weeks, particularly as U.S. forces defended against Iranian ballistic-missile and drone attacks. The United States had also used significant quantities of the same interceptor families while defending Israel before expending more during Operation Epic Fury, the analysis said.

The weapons carry high replacement costs. CBO estimated unit costs of roughly $4 million for a Patriot or SM-6 interceptor, $12 million for a THAAD interceptor and $28 million for a sophisticated SM-3 interceptor. The agency also linked the long replenishment timeline to the relatively low production rates for these systems.

The approximately $38 billion total includes expended munitions, equipment losses, increased flying hours, other operations and higher fuel costs. It excludes costs borne by other federal agencies and military operating costs already included in the federal budget. Beyond munitions, the largest cost categories were $10.4 billion for increased flying hours, $2.7 billion for fuel and $1.9 billion to replace equipment lost in battle. Those equipment losses included a THAAD radar destroyed by Iran.

The initial phase of Operation Epic Fury involved about 250 tactical aircraft, including roughly 90 aircraft from two carrier strike groups, along with an amphibious ready group. Bombers, airlifters, refueling tankers, other Navy vessels and Army air-defense, aviation and artillery units supported the operation.

CBO’s estimate is subject to considerable uncertainty because the Pentagon did not respond to the agency’s requests for information. Analysts instead relied on government databases and public reports. That limitation applies both to the campaign-cost estimate and to the calculation of interceptor depletion, which had to be inferred from procurement and expenditure data rather than from a disclosed inventory total.

A Defense Department inspector general report separately estimated the operation’s cost at $33.4 billion through June 29. The administration had requested $87.6 billion in supplemental funding in June, including $67.1 billion for the Defense Department. Of that request, $42.3 billion was identified as directly related to the conflict, an amount CBO said was about 10% higher than its estimate through Aug. 1.

The cost estimate remains open-ended. CBO projected that each additional month of fighting would cost roughly $2 billion to $3 billion if the intensity stayed relatively low, with higher costs possible if operations intensified. The agency also identified the depleted interceptor stocks as a particular concern in a conflict with China, which maintains large numbers of ballistic and cruise missiles.