WASHINGTON, March 19 (Reuters) - The U.S. military's request for an additional $200 billion to fund a war with Iran met with fierce opposition in the U.S. Congress on Thursday, with Democrats and even some Republicans questioning the need for the money after massive appropriations made to defense last year.

A U.S. official confirmed a Washington Post report that the Defense Department has asked the White House to approve a request to Congress for more than $200 billion to fund the war in Iran.

President Donald Trump has not yet sent a request to the Senate and House of Representatives for approval of this huge sum, and his administration has indicated that the figure may change.

Defense Secretary Pete Hegseth said at a press conference on Thursday, "I think that number could change, of course. Killing bad guys requires money... So, we'll go back to Congress and its members to ensure we have the appropriate funding for what has been done, and for what we may have to do in the future."

Initial indications suggest this war will be the most costly for the United States since the long conflicts in Iraq and Afghanistan. Administration officials informed lawmakers that the first six days of the war with Iran had already cost more than $11 billion.

Polls show that the war is unpopular, with only about one in four Americans supporting it.

The Republican-led Congress has already approved record funding for the military since Trump began his second term in January 2025. Last month, Trump signed the 2026 fiscal year defense appropriations bill, which totaled about $840 billion.

Last summer, despite strong opposition from Democrats, the Republican-led Congress passed a sweeping tax and spending cut bill that included $156 billion for defense.

Democrats questioned why the Pentagon needed more money, given recent cuts to social services, foreign aid and other programs, and said anyone who opposed the war should not vote to fund it.

Congress is requesting more information.

US and Israeli forces launched an attack on Iran on February 28. As the war neared the end of its third week, lawmakers, both Democrats and some Republicans, demanded more information about Trump's plans for a conflict that had killed thousands, disrupted the lives of millions more, and triggered turmoil in global energy and stock markets.

Democratic Representative Pramila Jayapal of Washington said in a speech to the House of Representatives, "We just heard that the Pentagon is requesting an additional $200 billion for this war. How on earth are we going to pay for that? This is absolutely ridiculous."

After receiving briefings from administration officials, lawmakers estimated that the cost of the war ranged between $1 billion and $2 billion per day.

Democratic Senator Chris Van Hollen of Maryland said the request should be non-negotiable with members of Congress. He wrote on X, "The best way to end this war, protect our troops, save civilian lives, and rein in an administration that disregards the law is to cut off funding. I absolutely reject it."

Even some of Trump's fellow Republicans appeared surprised by the proposed sum. Republican Senator Susan Collins, who chairs the Appropriations Committee, told reporters at the U.S. Capitol on Wednesday evening that she had not yet been informed of an additional $200 billion request.

She added that the total amount was "much higher than I expected, but I don't know how it was distributed."

She went on to say that she would likely want to hold a public hearing on this request.