The US defence department’s inspector general says the war with Iran has led to “shortfalls” in munitions and a bottleneck in resupply, contradicting President Donald Trump who has repeatly denied the US is facing shortages.
Trump has claimed US munitions supplies are “virtually unlimited” and said reporting otherwise is “fake news”.
But the independent watchdog said the US spent more than $22 billion on munitions from February through June, leading to “strategic inventory shortfalls”.
The BBC has contacted the White House for comment about the discrepancy.
The new report provides a first-of-its-kind, independent glimpse into US weapons stockpiles, data that is typically classified.
Previous estimates have painted a dire picture of the US shortages.
Over the course of the war, US forces have expended vast quantities of both long-range ground attack systems and the air and missile defences used to intercept incoming Iranian attacks.
A late July estimate from the Center for Strategic and International Studies, or CSIS, found that stocks of some interceptors – such as the Patriot missile and Terminal High Altitude Area Defense, or THAAD – were significantly depleted, in some cases by more than half.
The inspector general’s report did not disclose exactly how many of the weapons remain.
It did, however, note the inventory shortfalls and reveal “industrial base bottlenecks” for munitions resupply.
The report added that the defence department is now working to “streamline procurement processes and production lead times” to address the shortages and “respond rapidly to a contingency”.
Trump and other administration officials have sought to cast reports of shortages as false and “treasonous”.
In a 4 August X post, for example, Defence Secretary Pete Hegseth described news reporting on the shortages as “not true”.
And in a lengthy Truth Social post on 3 September, Trump claimed that the US had “virtually unlimited” amounts of ammunition and is “stockpiling and preparing for any contingency that could happen”.
The watchdog’s report also notes that equipment losses have totaled $3.7bn, with other $7.4bn in other expenditures. Overall, the US spent $33.4bn (£24.7bn) on the war from 28 Feb to 30 Jun.
A separate estimate released on Tuesday by the Congressional Budget Office put the total cost of the war at higher at $38bn, which includes replaced expended munitions and equipment lost in battle, increased flying hours and greater fuel costs.
Among the losses have been four F-15e fighter jets, a highly advanced F-35 Joint Strike Fighter and 30 MQ-9 drones destroyed in “various circumstances”.
When US and Israeli strikes began, Trump repeatedly said that the conflict would be over within weeks.
More recently, he said the conflict might not end until “right after” the November midterm elections in the US.
Polls show that the war is unpopular among Americans.
One Reuters/Ipsos poll released in early September found that only 23% of Americans – and only half of Republicans – believe the US to be in a stronger position with Iran compared with before hostilities broke out.
