The cost of the U.S. war with Iran is becoming a central fight in Washington as Congress weighs billions in defense spending and demands more detail from the Pentagon. That debate sharpened on September 17, 2026, when nearly every Senate Democrat asked Defense Secretary Pete Hegseth to provide what they called basic information about the war’s price tag. The request followed a Pentagon inspector general report that gave the fullest official public accounting so far of the conflict’s early costs.
Senators demand a fuller breakdown of the war bill
Senate Democrats, led by Sen. Elissa Slotkin of Michigan, sent a letter on September 17 demanding that Hegseth provide a detailed accounting of the Pentagon’s Iran war costs, according to Roll Call. The lawmakers said the department had repeatedly refused to share the kind of information previous administrations provided during wartime, and they asked for answers by September 30. Their request covered incurred costs, projected future costs, damage to installations, ship refurbishment and expected veterans’ benefits obligations.
The timing followed a new official cost marker from the Defense Department’s inspector general. According to AP’s reporting on that watchdog report, Operation Epic Fury cost an estimated $33.4 billion between February 28 and June 30, with major spending tied to munitions, aircraft and damage across the region. The report was described as the fullest official accounting yet of the war’s toll in taxpayer dollars, physical damage and military strain.
Lawmakers are also pressing for clarity because Pentagon figures have shifted over time. Sen. Chris Van Hollen said in a May 28 release that Acting Comptroller Jay Hurst told Congress on April 29 that the war would cost about $25 billion, then later revised that estimate to about $29 billion. By late July, AP reported, Hegseth told Congress the war had cost $37.5 billion, underscoring why lawmakers are asking for a line-by-line explanation of what is counted and what is left out.
This is a Washington oversight fight, but its reach is national because Congress is weighing whether to approve tens of billions more for the conflict. Roll Call reported that the administration’s $67.1 billion supplemental request, mostly intended for war-related costs, remains stuck in legislative limbo. Senators specifically asked the Pentagon to explain which parts of that request would cover bills already incurred, which would fund future operations and which are unrelated to military action against Iran.
What is confirmed is that the cost estimates continue to rise. The Congressional Budget Office said this week that the war had cost the Defense Department more than $38 billion through August 1 and could continue to cost up to $3 billion a month, according to AP. CBO also said the White House requested $87.6 billion in supplemental funding in June, and that $42.3 billion of that appeared to be directly related to the conflict.
What is not yet publicly known is the full breakdown senators say they need. Roll Call reported that lawmakers are still seeking details on damaged facilities, the use of $34 billion remaining from last year’s reconciliation law and the long-term obligations tied to veterans and readiness. The Pentagon had also declined to respond to CBO’s request for information, AP reported, leaving the budget office to rely on government databases and public reporting.
The immediate reason for the demand is the widening gap between administration estimates, watchdog findings and outside analyses. In March, Sen. Jack Reed, the top Democrat on the Senate Armed Services Committee, asked Hegseth to report how much the department had spent since the initial strikes on February 28, what the daily costs were and what it would take to replenish munitions and aircraft losses. Reed also asked when the administration would submit a supplemental request because the operation had not been included in the fiscal 2026 budget.
Subsequent reports have added to the pressure. AP said the inspector general found the war created strategic inventory shortfalls and exposed munitions resupply bottlenecks, while also documenting damage to U.S. bases and diplomatic facilities across the Middle East. The report said Iranian strikes damaged or destroyed hundreds of structures at bases in Bahrain, Kuwait, Qatar, the United Arab Emirates, Saudi Arabia, Iraq, Oman and Jordan, and that damage to diplomatic facilities was estimated at $184 million.
For residents and taxpayers, the practical takeaway is that the cost debate is no longer only about one headline figure. Senators are now asking the Pentagon to show what has already been spent, what future commitments may follow and what additional funding Congress may still be asked to pass. As of this week, the most current nonpartisan estimate from CBO puts the Defense Department’s cost above $38 billion through August 1, while the earlier watchdog report remains the clearest official snapshot of the war’s first four months.