The Pentagon told Congress today the Iran war has cost $29 billion – up $4 billion in two weeks – and Harvard estimates the final bill will top $1 trillion
Defense Secretary Pete Hegseth told the House Appropriations Defense Subcommittee on May 12, 2026, that the U.S. war in Iran has now cost $29 billion. Two weeks earlier, the figure stood at $25 billion. The $4 billion jump in 14 days caught lawmakers in both parties off guard and set off the sharpest confrontation over war spending since the conflict began earlier this year.
Outside the hearing room, the long-term outlook is far grimmer. Linda Bilmes, a public finance economist at the Harvard Kennedy School who built her reputation calculating the true costs of the Iraq and Afghanistan wars, projects the Iran conflict will ultimately exceed $1 trillion once long-term obligations are counted.
Inside the hearing: pointed questions, few answers
Hegseth appeared alongside senior military officials at a scheduled budget hearing that was supposed to be a routine walk-through of the defense budget. Instead, it became a two-hour interrogation of the war’s trajectory and its mounting price tag.
Republicans who typically defer to the Pentagon on wartime spending demanded to know why the burn rate is accelerating rather than leveling off. Democrats pressed on the absence of any publicly stated endgame. Both sides zeroed in on a concrete worry: the campaign is chewing through precision-guided munitions and air defense interceptors at a pace that could weaken American deterrence in the Pacific and Europe.
According to wire-service reporting on the session, Hegseth acknowledged the Pentagon has had to shuffle weapons inventories among combatant commands to keep the Iran operation supplied. He insisted no theater has been left unable to meet its core obligations. Several lawmakers responded that the assurance rang hollow without public data to back it up.
No itemized breakdown of the $4 billion two-week increase has been released. It remains unclear how much of the spike stems from intensified airstrikes, how much from troop support costs, and how much from logistics. The Pentagon has not said whether the acceleration reflects a deliberate escalation or simply the compounding expense of sustaining operations at their current tempo.
Why a Harvard economist says the real cost will hit $1 trillion
Bilmes co-authored the landmark study The Three Trillion Dollar War on Iraq and Afghanistan with Nobel laureate Joseph Stiglitz. She has now applied the same framework to Iran, breaking the costs into three layers. (As of late May 2026, no direct link to the Iran-specific analysis has been made publicly available through the Harvard Kennedy School website, so the claims below are based on Bilmes’s public statements rather than a published paper.)
Direct operating costs. Airstrikes, fuel, troop deployments, and the logistics chain that keeps them running. Bilmes estimates these expenses are running around $2 billion per day during peak operational periods, a figure she has cited in public commentary but has not yet published with full supporting methodology. For comparison, at the height of the Iraq and Afghanistan wars combined, daily U.S. military spending in those theaters was roughly $700 million to $800 million, according to Congressional Research Service data. Her figure implies a rate more than double the most expensive phase of those earlier conflicts. The Pentagon has not independently verified the estimate, and some defense analysts consider it aggressive. Bilmes argues it reflects the higher unit costs of modern precision weapons and the geographic complexity of striking targets across Iranian territory, but the number should be treated as a contested projection rather than an established fact.
Medium-term replacement costs. This is the accounting gap most budget debates ignore. The Pentagon values expended munitions at their original purchase price. Replacing a Tomahawk cruise missile or a JDAM kit today costs significantly more than it did when those weapons were first bought, sometimes decades ago. Bilmes contends that switching to replacement-cost accounting, which reflects what the government will actually pay to rebuild stockpiles, adds hundreds of billions to the war’s real price tag.
Long-term veteran care. Disability payments, medical treatment, and other benefits for service members can stretch 50 years or more after a conflict ends. In the Iraq and Afghanistan wars, these obligations grew into the single biggest cost category, eventually exceeding direct combat spending. Bilmes argues that applying similar actuarial assumptions to the Iran war makes $1 trillion not an upper bound but a conservative floor, particularly if operations continue at or near their current intensity for several more months.
How $29 billion compares to earlier wars at the same stage
Scale matters here. The Congressional Research Service estimated that the first several months of the Iraq invasion in 2003 cost roughly $51 billion in inflation-adjusted terms for the full fiscal year. The Afghanistan war’s early phase was cheaper, running about $20 billion in its first year. The Iran conflict’s $29 billion price tag, reached in a fraction of that time, suggests a spending velocity that outpaces both predecessors. That comparison is imperfect because each war involved different force structures and objectives, but it gives taxpayers a rough sense of where things stand.
What Congress does next will shape the final number
The hearing exposed a fault line that will define the next round of budget negotiations. Some members signaled they want tighter conditions on future war funding: more frequent reporting on munitions inventories, clearer benchmarks for operational progress, and a requirement that the administration present a diplomatic framework before requesting additional appropriations.
Others warned that restrictive language could hamstring commanders during active combat. That tension between asserting congressional oversight and avoiding micromanagement of military operations is familiar from every major American conflict since Vietnam, but the speed at which costs are climbing gives it new urgency.
The $29 billion figure carries the weight of official testimony delivered to a congressional committee. Bilmes’s $1 trillion projection is an expert forecast built on historical patterns and a broader definition of cost. The first number tells taxpayers what has been spent so far. The second warns what the full financial legacy may look like once every bill comes due, from the last missile fired to the last veteran’s medical claim processed decades from now.
Why the next supplemental funding vote is the real test of congressional resolve
With the burn rate still climbing and no public timeline for winding down operations, the window for Congress to assert control over the war’s cost is narrowing. The next supplemental funding request, expected within weeks, will test whether the bipartisan frustration on display May 12 translates into actual spending constraints or fades back into deference.
Warren Cohen is a finance writer based in Phoenix, Arizona, covering personal finance topics including credit, banking, and beginner investing. He earned his degree in business administration from Arizona State University and began his career working in consumer finance, where he gained direct experience with lending and credit systems. He now writes for personal finance websites and fintech platforms, focusing on clear, practical content that helps readers make informed financial decisions.
