The United States-Israel war on Iran has cost an estimated $3.7bn in its first 100 hours, or roughly $891.4m per day, driven largely by heavy munitions use, according to analysis by the Washington think tank Center for Strategic and International Studies (CSIS). The conflict entered its seventh day as the US struck Iran with stealth bombers and advanced weapons systems.
Researchers Mark Cancian and Chris Park found that only a small portion of that $3.7bn was already budgeted; about $3.5bn remains unbudgeted. That shortfall means the Pentagon will likely need to request additional funding soon, a politically sensitive move that could become a focal point for opposition to the war. Rising domestic concerns over cost of living, inflation, and higher gas prices tied to the conflict are likely to erode public support and are reportedly straining former president Trump’s “America First” base, which he had pledged would avoid foreign wars.
Because the Department of Defense has released limited operational specifics, CSIS based its figures on Congressional Budget Office estimates for operations and support costs by unit, adjusted for inflation and unit size, and added 10% to account for a higher operational tempo. The analysis estimates more than 2,000 munitions of various types were expended in the first 100 hours and calculates a $3.1bn cost to replenish those munitions on a like-for-like basis, with replenishment spending rising by about $758.1m per day.
US Defense Secretary Pete Hegseth has said the US bombardment is “about to surge dramatically,” with more fighter squadrons, defensive capabilities and bomber pulses. CSIS notes that while air campaigns often slow after an intense opening phase, the unbudgeted costs here will remain substantial. Unlike recent US operations — such as the operation against Venezuela’s Nicolás Maduro, where most expenses had been budgeted — this campaign will likely require new funds. The report suggests the administration may seek a supplemental appropriation to cover military costs and other unexpected government expenses, as was done early in the Iraq and Afghanistan wars, but warns such requests will invite political contention.
The conflict has already produced a severe human toll. Iranian authorities and aid agencies report more than 1,332 people killed in Iran since the strikes began, with UNICEF saying at least 181 children are among the dead. In Lebanon, the health ministry reports at least 123 killed in a fresh wave of strikes. At least six US servicemembers, 11 people in Israel, and nine people in Gulf Arab countries have also died.
