CBO: Iran war costs top $40 billion

The Congressional Budget Office said on Tuesday that U.S. military operations in Iran have cost more than $40 billion and will continue to run between $2 billion and $3 billion per month, pressuring energy markets through heightened Gulf shipping risk.

CBO Director Phillip L. Swagel wrote that the "main opportunity cost" has been heavy use of missile‑defense interceptors, leaving the United States with a reduced inventory for years and a shortfall if confronted by an opponent with large missile arsenals.

Missile interceptor shortfall

The report said the analysis relied on public databases and government reports after the Defense Department did not respond to CBO requests for information, and that its estimates are therefore subject to considerable uncertainty. Data cited in the analysis showed gas prices had risen about 21% five months after the campaign began, and CBO projected the conflict would boost inflation by 0.5 percentage points in the first quarter of 2027, driven mainly by energy costs and disruptions near the Strait of Hormuz.

CBO did not assign dollar values to U.S. personnel casualties or to longer‑term veterans care, nor did it estimate repair costs for damaged equipment and bases absent DoD data.

If the Defense Department supplies additional information, CBO could revise its figures; market participants and lawmakers should watch for any updated estimate by October 31, 2026.