The Pentagon says the US has spent $37.5 billion on the war with Iran and is seeking additional funding from Congress.
Lawmakers questioned the Trump administration over the conflict's costs, strategy and lack of congressional briefings.
The war has killed 18 US troops, injured hundreds of service members and continued to fuel tensions across the Middle East.
The United States has spent $37.5 billion on its war with Iran so far, Defence Secretary Pete Hegseth told lawmakers on Tuesday during his first appearance before sceptical lawmakers since heavy US bombing resumed, where he sought urgent funding for the conflict.
The hearing highlighted the rising cost of a conflict that has stretched the Pentagon's military budget, increased pressure on Congress to approve fresh defence spending and left American forces facing sustained attacks across the Middle East. According to Reuters, Democrats have stepped up attacks on the Trump administration by linking the unpopular war with affordability concerns, while both Democrats and Republicans have criticised the White House for failing to keep Congress informed about its strategy. AP reported that although the conflict has largely been fought through missiles, drones and air strikes rather than ground combat, it has continued to claim the lives of US service members stationed across the region.
Pentagon seeks urgent funding as war costs mount
Hegseth told the Appropriations Committee that the $37.5 billion estimate includes both money already spent on the conflict and anticipated costs through September 30. It was not immediately clear how the Pentagon arrived at the figure. According to Reuters, a source had said in March that the Trump administration estimated the first six days of the war alone had already cost at least $11.3 billion.
Last month, President Donald Trump asked Congress to approve nearly $90 billion in additional funding, most of it linked to the Iran conflict, setting up another fight with lawmakers increasingly frustrated by the war ahead of the November midterm elections, Reuters reported. With Republicans holding only narrow majorities in both the House of Representatives and the Senate, appropriations legislation is expected to require Democratic support.
The war has also strained the Pentagon's nearly $1 trillion budget. Hegseth warned lawmakers that military training would have to be reduced without immediate funding and urged Congress to also approve the administration's proposed $1.5 trillion defence budget for 2027.
"Not funding this department at $1.5 trillion, I believe, is the greatest threat that our nation faces," Hegseth said.
Chairman of the Joint Chiefs of Staff General Dan Caine acknowledged that while the Pentagon would ensure service members continued to be paid, maintenance work and investments in future military capabilities could suffer if additional funding was not approved.
Congress questions White House strategy as fighting continues
According to Reuters, the funding debate comes less than six months before the November midterm elections, where Trump's Republicans could face an uphill battle to retain their majorities in both chambers of Congress. Democrats, riding high in public opinion polls, have increasingly linked the cost of the Iran war to affordability issues facing American voters.
Lawmakers from both parties also complained that the administration had failed to keep Congress informed since the United States and Israel began bombing Iran on February 28.
"The president is threatening escalation and war crimes, and suggesting this could be another forever war," Senator Patty Murray, the top Democrat on the Appropriations Committee, said at the hearing. Trump has repeatedly issued severe threats against Iran, including against civilian infrastructure, which critics say would be a war crime.
"The reason why they (people) are so upset with you and this administration is because the words you have used in the past don't add up," Democratic Senator Kirsten Gillibrand said. "It's either over, or it's not over. It's within two weeks, or it's not two weeks, it's either missiles or it's not missiles."
According to Reuters, a fragile ceasefire between the United States and Iran collapsed earlier this month, and both countries have since resumed daily strikes.
Over the past week, Trump has threatened to expand US operations by targeting Iranian energy facilities and bridges, deploying ground forces to seize Iran's Kharg Island oil hub and bombing the underground nuclear-linked facility known as Pickaxe Mountain. On Tuesday, he said the United States would take out the mountain facility "pretty soon".
American military deaths continue as conflict spreads
The conflict has also pushed up casualties among US personnel deployed across the Middle East. Reuters reported that the Pentagon told lawmakers the number of US troops killed had risen to 18 over the weekend, while roughly 430 service members have been injured. The Pentagon also said on Monday that 100 personnel had been injured since July 7, adding that 96% had already returned to duty.
AP, citing the latest military announcements, reported that the publicly confirmed death toll stood at 17. The latest fatality occurred in northern Iraq on Saturday when a US service member was killed during the controlled detonation of unexploded ordnance from a downed Iranian drone. Another service member suffered minor injuries. The military said it would release further details only after families had been notified.
According to AP, the first American fatalities came soon after the war began. Six US soldiers from an Iowa-based supply and logistics unit were killed in an Iranian drone strike on a civilian port in Kuwait, where they were working inside an undefended shipping container-style building. A seventh soldier later died from wounds sustained during a March 1 Iranian attack on Prince Sultan Air Base in Saudi Arabia.
Later in March, six more service members were killed when a KC-135 aerial refuelling aircraft supporting operations against Iran crashed in Iraq following an unspecified incident involving another aircraft in friendly airspace, AP reported.
The US military also said a Navy pilot died after a helicopter crashed in the Arabian Sea on July 1. The Navy initially described the incident as an emergency landing and said there was "no indication the emergency was caused by hostile action". Three other sailors aboard the helicopter survived.
On Friday, two more US service members were killed in Jordan while defending against Iranian ballistic missile and drone attacks. A third service member was initially reported missing, and AP said unidentified remains later recovered were being examined.
The conflict has also taken a toll beyond the US military. According to AP, Iranian authorities said at least 50 people have been killed and more than 500 wounded in US strikes over the past three weeks, including eight people killed in a strike on a bridge on Friday. People working aboard ships, foreign workers in Gulf countries, and civilians in Israel and Lebanon have also been killed in the conflict, according to AP.
