The six-month-old US war against Iran has cost Washington about $38bn, with the figure expected to rise by another $3bn monthly, according to the Congressional Budget Office.
The nonpartisan US congressional budget watchdog said in a report released on Tuesday that the calculation covered expenses incurred through August 1.
It also projected that the conflict could increase US inflation by 0.5 per cent during the first three months of 2027.
The rising cost of the war has put pressure on US military ammunition stockpiles and increased energy prices, while raising concerns about the country’s readiness to respond to another major conflict.
The CBO said the bulk of the expenditure came from the rapid use of military munitions and estimated that replenishing US stockpiles could take up to five years.
The figure is close to the $37.5bn Defence Secretary Pete Hegseth reported during a Senate hearing on July 21.
Pentagon disputes munitions shortage
The CBO said the Department of Defense did not cooperate with its financial review.
White House spokeswoman Anna Kelly defended President Donald Trump’s military campaign, describing it as “decisive action” aimed at preventing Iran from harming US personnel or interests.
She said the US military had “more than enough munitions, ammo, and stockpiles” to meet Trump’s strategic objectives.
Chief Pentagon spokesman Sean Parnell also rejected the CBO’s findings on ammunition shortages.
“We have everything required to strike at the time and place of the president’s choosing,” Parnell said.
However, the CBO said shortages of critical weapons, including missile interceptors, could affect the Pentagon’s ability to respond to another major conflict.
At the July Senate hearing, Hegseth had requested nearly $90bn in emergency funding to replenish US ammunition supplies.
“Without these funds, we face critical shortfalls,” he said.
War cost excludes some expenses
The CBO’s $38bn estimate does not include the costs of recent attacks on commercial vessels in the Strait of Hormuz or attacks on US military installations in the region.
It also excluded borrowing costs used to finance the war, which could add tens of billions of dollars to the final bill.
The Pentagon’s inspector general had earlier put the cost of the war at $33.4bn through June 19.
The watchdog also reported that Iranian attacks damaged or destroyed hundreds of buildings at US military bases in the Middle East, as well as fighter jets, refuelling aircraft and drones.
Eighteen US service members have died in the conflict, according to the report.
Strait of Hormuz drives energy costs
The conflict has also affected global energy markets.
Attacks around the Strait of Hormuz and on energy facilities in neighbouring Gulf countries have pushed up energy prices for consumers and producers.
The waterway handles about 20 per cent of global oil shipments under normal conditions.
The higher war expenditure is also adding pressure to US government finances, with the country’s total public debt surpassing $40tn in August.
The CBO review was conducted at the request of Brendan Boyle, the senior Democrat on the US House Budget Committee.
Boyle said the report showed that the war had cost American taxpayers tens of billions of dollars while contributing to higher prices.
The US conflict in Iran is now being compared with its previous wars in Iraq and Afghanistan. Reuters reported that the Iraq war cost about $2tn, while the two-decade conflict in Afghanistan cost about $2.3tn, according to Brown University’s Costs of War project.
