“Obviously, it takes money to kill bad guys,” Defense Secretary Pete Hegseth said when asked about the request during a news conference on Thursday, adding: “As far as the $200 billion, I think that number could move.”

On Capitol Hill, the sum — nearly a quarter of the country’s entire annual defense budget — is already raising eyebrows among some moderate Republicans who would be key to approving the funds.

“It’s considerably higher than I would have guessed, but I don’t know how it’s broken down,” Senator Susan Collins, Republican of Maine and the head of the chamber’s Appropriations Committee, told reporters Wednesday evening. The White House had not passed along any request to Congress, she said.

Senator Lisa Murkowski, Republican of Alaska and a key swing vote, said that the Trump administration would have to make a more concerted effort to engage Congress on the war before such a request could be approved.

“You just can’t come up here with an invoice and say, you know, ‘pay this’ and expect to have great cooperation going forward,” she told reporters on Wednesday.

It was not immediately clear how long the Pentagon intended for the $200 billion for the Iran war to last, or what operations it would cover. In 2014, the Congressional Research Service calculated that the United States spent $815 billion in direct costs for the war in Iraq over 13 years. A recent report from the Council on Foreign Relations, compiled from official government statistics, found that the United States had dedicated $188 billion in aid to shore up Ukraine’s war effort since Russia invaded in early 2022.

The funds for those wars were not approved as lump sums, but meted out over several appropriations cycles after extended, and oftentimes heated, debate about mounting costs.

Last week, Pentagon officials told lawmakers that the first six days of the war against Iran had cost more than $11.3 billion. Since then, President Trump has threatened to escalate the fighting, including floating the idea of putting American troops on the ground even as he has alternated the threats with suggestions that the United States might conclude its military campaign soon.

But the $200 billion figure suggests that the U.S. military is preparing for an extended engagement in Iran.

The extent of the damage was not clear but the attack has spooked investors, and analysts warned that it could take months to repair.

Here is what to know about Ras Laffan and why the threat to Qatar’s energy infrastructure is having a global impact.

How important is Ras Laffan?

The Ras Laffan complex is the heart of Qatar’s natural gas processing operations.

The facility is approximately a third of the size of New York City and was built 30 years ago about 50 miles from the capital, Doha. It accounts for roughly a fifth of the global supply of liquefied natural gas.

Qatar is the world’s third-largest exporter of L.N.G., and has made hundreds of billions of dollars from the industry over decades, helping to turn itself into a global energy superpower.

Most of Qatar’s natural gas comes from the North Dome field, which is part of the world’s largest offshore natural gas reservoir. Qatar shares the field with Iran.

How will the damage hit the global energy market?

Qatar is a major supplier to Europe and Asia, and the attack sent European natural gas prices surging by as much as 30 percent on Thursday.

Qatar had stopped exporting L.N.G. earlier in the war, which was sparked by Israeli and U.S. attacks on Iran, and some analysts worry that the disruption to Ras Laffan mean resuming the trade could take months once the conflict ends.

“The issue of taking out an L.N.G. terminal is they take a while to repair,” said Sarah Emerson, an energy analyst with the Center for Strategic and International Studies, a think tank. “This is not a simple facility to replace.”

“This is potentially a really significant disruption to the global natural gas market,” she added. “There’s a lot of countries that export a little, there aren’t that many countries that export a lot.”

The United States is the world’s biggest L.N.G. exporter, but it has maxed out its capacity on what it can sell overseas, Ms. Emerson said.

Is this a new front?

In a joint statement, the foreign ministers for several Arab and Muslim countries condemned the “deliberate” Iranian attacks on civilian infrastructure, including “oil facilities, desalination plants, airports, residential buildings, and diplomatic premises.”

Iran is following through on its threats to strike the energy infrastructure of American allies in the Persian Gulf if its energy sites are targeted, said Justin Dargin, a nonresident senior fellow at the Middle East Council of Global Affairs, a Doha-based think tank.

More of these types of attacks are part of Iran’s strategy to inflict pain on the Gulf countries and persuade them to pressure the U.S. and Israel to “wrap this war up,” he said.

If more of Iran’s energy infrastructure is attacked, Mr. Dargin added, “Iran will start to target more of the backbone of energy facilities in the Gulf region.”