Defense Secretary Pete Hegseth could ask Congress for as much as $200bn (£150bn) more in funding because of the war in Iran, he indicated during a news conference.
The Washington Post and other US media reported that the Pentagon had asked the White House to approve a $200bn request to Congress for Iran war funding, according to senior administration officials.
Asked about the funding on Thursday, Hegseth told reporters: "It takes money to kill bad guys".
"We're going back to Congress and our folks there to ensure that we're properly funded," he said.
US President Donald Trump's economic adviser Kevin Hassett said on Sunday that the war in Iran had already cost the US $12bn.
