The CBO said the cost could rise by another $2 billion to $3 billion for every additional month of fighting, depending on the intensity of the conflict.
The US war with Iran has cost the Pentagon about $38 billion through August 1, with the conflict also leaving the military with fewer missile-defence interceptors for a potential future conflict with China, according to a new report by the nonpartisan Congressional Budget Office (CBO).
The CBO said the cost could rise by another $2 billion to $3 billion for every additional month of fighting, depending on the intensity of the conflict. The estimate covers the cost of replacing used munitions and equipment, increased flying hours, military operations and higher fuel costs.
War Bill Could Rise Further
The CBO said the $38 billion figure reflects the intense initial phase of the conflict, which lasted just over a month, while less intense combat operations remain ongoing.
If violence remains at the lower levels seen in May and June, another month of fighting would cost about $2 billion, the report said. If fighting returns to the intensity seen in July, the monthly cost could reach $3 billion or more.
The CBO noted that its estimate does not include some costs borne by other parts of the federal government or basic military operating costs already included in the federal budget.
Missile Stocks Take Major Hit
One of the biggest costs has been the use of missile-defence interceptors. The Pentagon has used large numbers of Patriot, THAAD, SM-3 and SM-6 interceptors against ballistic missile attacks.
The CBO estimates that the US has probably used between half and two-thirds of its inventory of these interceptors since June 2025.
The report said the US now has fewer interceptors available for a potential conflict with China, which has a much larger ballistic and cruise missile arsenal than Iran had when the US operation began.
“Having used a large portion of its missile defense inventory in combat operations against Iran, DoD now has fewer interceptors on hand to use in a potential conflict with the PRC,” the CBO said.
