The US is facing mounting costs as it races to replenish its stocks of missiles and missile interceptors that it used in the early stages of the Iran war.
A report released this week by the Congressional Budget Office found that the war had cost at least $38 billion as of August 1. The biggest single expense came from firing missile-defence interceptors and munitions, which it said will leave the US with a reduced inventory "for several years".
The CBO accounting found the war could have far-reaching consequences for US defence and the domestic economy.
The shortfall in critical munitions, including missile interceptors, could hamper the Pentagon's response in the event of another major conflict, such as any hostilities involving China and Taiwan, the CBO noted.
The US has been firing Patriot and Thaad interceptors to protect its troops and allies from Iranian missiles and drones in the Middle East.
A Pentagon inspector general's report acknowledged "strategic inventory shortfalls" and industrial bottlenecks for resupply.
According to an analysis by the Centre for Strategic and International Studies, the number of Patriot interceptors fell from 2,330 at the start of the conflict to fewer than 850 by the end of July. Thaad stockpiles, meanwhile, dwindled to about 250 from 452.
"Diminished stockpiles may force the United States and its coalition partners to take more risks with interceptions," CSIS noted. "There are no good alternatives to Patriot and Thaad for ballistic missile defence."
In its fiscal year 2027 budget request, the US Army has asked for $12.2 billion for Patriot PAC-3 MSE missiles, more than nine times its request for the previous year of $1.3 billion. The request would fund 2,798 missiles, compared with 233 in the 2026 fiscal year.
The same request includes $11.4 billion for Thaad interceptors. That compares with about $1.5 billion requested for Thaad in fiscal year 2026. The recent request would fund 857 Thaad interceptors.
The reduced stockpiles of US missiles have raised concerns about the country's ability to respond to any other conflicts and added pressure on an already stretched federal budget.
At a July hearing in the Senate, Defence Secretary Pete Hegseth pleaded for nearly $90 billion in emergency funding to restock munitions supplies.
“Without these funds, we face critical shortfalls,” Mr Hegseth said.
The Pentagon’s inspector general reported that Iranian attacks had damaged or destroyed hundreds of buildings on US bases in the Middle East, as well as aircraft including fighter jets, refuelling planes and drones.
President Donald Trump said in a social media post last week that the US is “producing more exquisite and elite weapons than at any time in our history".
White House spokeswoman Anna Kelly said that the US military has "more than enough munitions, ammo and stockpiles to serve all of the Commander-in-Chief’s strategic goals and beyond".
The Pentagon has announced tens of billions of dollars in production deals with defence contractors in recent weeks. Last month, it announced deals with Raytheon, Northrop Grumman and Lockheed Martin to boost production of missiles and missile parts.
The CBO report does not include some costs from the war, such as damage to US bases in the region. It also did not factor in the borrowing expenses associated with financing the conflict, which could add tens of billions of dollars to the total cost.
