The war with Iran has cost the US some $37.5bn (£28bn) so far - an increase of nearly $8bn since the last estimate in May, Defence Secretary Pete Hegseth has said.
In his first appearance before the Senate Appropriations Committee since hostilities between the US and Iran restarted, Hegseth said that military training would have to be curtailed unless lawmakers approved an urgent funding boost.
He said he was seeking $87bn in congressional funding for his department, with $67bn of that destined for operations in the Middle East.
The hearing was interrupted several times by anti-war protesters, with some shouting “stop bombing our children in Iran and Palestine”.
Hegseth’s appearance before the committee came at a pivotal time in the war after three US soldiers were killed in the Middle East.
The White House asked Congress in April for $1.5tn for the Pentagon over the next fiscal year, which would raise American military spending to an all-time high in the modern era.