$3.7 Billion for 100 Hours: CSIS Puts Early Price Tag on U.S. Strikes Against Iran

The bill—and who pays

The first 100 hours of U.S. military operations against Iran could cost about $3.7 billion, according to a March 5 analysis by the Center for Strategic and International Studies (CSIS) cited by Chinese outlet Huxiu (虎嗅). Most of that—roughly $3.5 billion—is not in current budgets and would require a supplemental appropriation or a budget reconciliation measure. At what price, and for how long? With President Donald Trump and Defense Secretary Pete Hegseth saying the campaign may last weeks, the funding gap is poised to become a flashpoint in Congress and a focal point for public opposition to a new Middle East war.

What drives the cost

Munitions dominate the tally. CSIS estimates about $3.1 billion to replace expended weapons in the opening phase alone, with daily replenishment needs rising by an additional $758 million if operations persist. Operational costs are comparatively modest—about $196 million over the first 100 hours—while combat losses and infrastructure repairs add roughly $350 million. The think tank built its estimate from inflation-adjusted Congressional Budget Office (CBO) unit operating costs and layered on a 10% premium for higher wartime tempo, consistent with past Office of Management and Budget practices from Iraq and Afghanistan. Only around $200 million of the near-term spend is reportedly pre-budgeted.

Force mix and munitions burn

Pentagon disclosures have been sparse, but U.S. Central Command briefings and service chiefs’ statements sketch a large footprint. Admiral Brad Cooper has indicated more than 200 fighter aircraft are engaged, including about 50 stealth F-35s and F-22s, 110 legacy fighters, and roughly 80 carrier-based jets. Two aircraft carriers, 14 destroyers, and three Littoral Combat Ships are positioned across the Arabian Sea, the Persian Gulf, and the Eastern Mediterranean; Navy operating costs for the first 100 hours are put at $64.5 million and about $15.4 million per additional day. CSIS infers more than 2,600 precision weapons may have been expended in under 100 hours—over 2,000 targets struck, at an estimated 1.3 munitions per aimpoint—beginning with 160+ Tomahawk cruise missiles before shifting to closer-in precision strikes over Iran. Low-Cost Unmanned Combat Air System (LUCAS) drones reportedly saw their first combat use from at least one LCS.

Politics and risks

The estimate lands amid a dramatic escalation: on February 28, joint U.S.-Israeli airstrikes reportedly killed Iran’s Supreme Leader Ayatollah Ali Khamenei, prompting retaliatory attacks and raising regional risk in a sanctions-laden environment. Defense leaders say the pace of strikes may stabilize, and the Pentagon is shifting toward cheaper ordnance as Iranian drone and missile launches reportedly decline—factors that could temper the burn rate. But with the bulk of spending unbudgeted and dependent on a divided Congress, the central question lingers: who pays for a conflict that could run for weeks, and at what strategic return?