WASHINGTON: The United States has acknowledged that its war on Iran resulted in “strategic inventory shortfalls and revealed industrial base bottlenecks for munitions resupply” for America.

The admission came in the first Pentagon Inspector General’s report on the US-Israeli war on Iran. The report, released on Monday, provides a detailed account of the campaign’s cost, damage and impact on American weapons stocks, confirming some of the concerns that news organisations had reported for months.

More than 50,000 US service members took part in the campaign, flying thousands of combat missions and expending $22.3 billion worth of munitions, according to the report.

The report, covering the period between February 28 and June 30, puts the direct cost of the war at about $33.4bn. Of that amount, $22.3bn was spent on munitions, $3.7bn on equipment losses and $7.4bn on other expenditures.

The estimate does not include the cost of repairing damaged facilities, replacing aircraft or replenishing critical weapons stocks.

That distinction explains why Pentagon estimates of the war’s cost have varied.

In late July, US Defence Secretary Pete Hegseth told Congress that the war had cost the department $37.5bn. Separately, NBC News reported in July that US officials and people familiar with internal estimates put the eventual cost between $80bn and $100bn.

Those higher estimates apparently included costs not captured in the Inspector General’s four-month calculation, including repairs, replacement of aircraft and replenishment of weapons.

The Inspector General’s report nevertheless confirms one of the most closely watched concerns of the war: the effect of the campaign on US munitions stocks.

The report said the conflict “resulted in strategic inventory shortfalls and revealed industrial base bottlenecks for munitions resupply”.

The finding aligned with concerns about rapidly falling stocks, reported by various news outlets well before the Inspector General’s assessment was released.

In March, The Washington Post reported that the US military had fired more than 850 Tomahawk cruise missiles in the first four weeks of the conflict, prompting concern among some Pentagon officials about the rapid depletion of precision weapons. The White House and Pentagon, however, said at the time that the United States had sufficient stocks to carry out the operation.

By late April, Pentagon officials were putting the cost of the first two months of the operation at about $25bn, saying that most of the amount was for munitions. Independent analysts questioned whether that figure captured the full cost of the war, given equipment losses, damage to bases and other expenses.

The Inspector General’s report provided an official acknowledgement that the campaign did impose significant pressure on weapons inventories.

The report said the Defence Department was responding by streamlining procurement and production lead times and by stockpiling critical materials, components and selected munitions so that it could respond more rapidly to another contingency.

The physical damage was also extensive, according to the report.

Iranian strikes damaged or destroyed hundreds of buildings and other structures at US bases in Kuwait, Bahrain, Qatar, the United Arab Emirates, Saudi Arabia, Iraq, Oman and Jordan, it said. Dozens of American aircraft and drones were destroyed or damaged.

The Pentagon report also confirmed that Iran attacked the US Navy’s principal logistics hub in Bahrain with drones and ballistic missiles. It also recorded the destruction of at least 30 large US drones during the period covered by the assessment.

The damage extended to American diplomatic facilities.

US diplomatic properties in Iraq, Kuwait, Saudi Arabia and the United Arab Emirates suffered an estimated $184 million in physical damage, according to the report. The State Department separately reported $113m in overall costs related to the conflict, including nearly $80m for contingency planning and evacuations.

More than 20,000 US military and diplomatic personnel were also displaced during the conflict, according to the assessment.

The findings confirmed a picture that had been emerging from independent reporting: “Operation Epic Fury” was not simply a campaign in which the United States fired large quantities of weapons at Iranian targets. It also imposed substantial demands on the American military’s ability to replace those weapons, protect its regional bases and move personnel and equipment away from threatened facilities.