The cost of the United States' war in Iran has risen to US$37.5 billion (NZ$64b) so far, US Defence Secretary Pete Hegseth says, as he faces sceptical lawmakers for the first time since heavy bombings resumed to seek urgent funding for the unpopular conflict.

The war with Iran has cost $37.5 billion so far, according to US Defense Secretary Pete Hegseth, but the bill is likely much higher, experts have told CNN.

WASHINGTON (AP) — Defense Secretary Pete Hegseth faced questions and protests Tuesday over the U.S. war with Iran, which he estimated has cost $37.5 billion so far, as Republicans…

Latest estimate before that, in May, was $7.5bn lower

At a Senate budget hearing on Tuesday, US Defense Secretary Pete Hegseth estimated that the war with Iran had so far cost $37.5 billion.