WASHINGTON -- The Pentagon's latest estimate puts the cost of the US war against Iran at 37.5 billion US dollars so far, US Defense Secretary Pete Hegseth said on Tuesday as the Trump administration seeks more funding for the conflict.

Supplemental funding for the war with Iran is "urgent, necessary," Hegseth testified during a Senate budget hearing.

"Without these funds, we face critical shortfalls," Hegseth asserted.

His remarks came as Republican lawmakers sought congressional approval for US President Donald Trump's proposed 1.5-trillion-dollar defense budget.

In June, White House Office of Management and Budget Director Russell Vought told lawmakers that the war with Iran cost US taxpayers around 30 billion dollars.