President Biden on Friday paused the permitting process for new liquefied natural gas export facilities in order to analyze their impact on climate change, the economy and national security.

“In every corner of the country and the world, people are suffering the devastating toll of climate change,” Mr. Biden said in a statement. “This pause on new L.N.G. approvals sees the climate crisis for what it is: the existential threat of our time.”

The move could spell trouble for what would be the largest export terminal in the country, a $10 billion proposed project in Louisiana that has drawn scrutiny for its potential environmental impact.

Mr. Biden’s election-year decision is viewed as a win for climate activists who have pressed the administration to curb fossil fuels at a time when greenhouse gas emissions must fall rapidly to stave off climate catastrophe.

Gas, which is primarily composed of methane, is cleaner than coal when it is burned. But methane is a much more potent greenhouse gas in the short term, compared with carbon dioxide. And it can leak anywhere along the supply chain, from the production wellhead to processing plants to the stovetop. The process of liquefying gas to transport it is incredibly energy intensive as well, creating yet more emissions.

More than 150 scientists signed a Dec. 19 letter to Mr. Biden, urging him to reject the Louisiana project, known as Calcasieu Pass 2, often referred to as CP2, and additional proposed facilities.

In just eight years since it first began shipping natural gas overseas, the United States has become the world’s leader in L.N.G. exports.

The country has seven terminals with another five approved facilities under construction. An additional 17 projects have been seeking permits. The move comes a month after the United States joined nearly 200 nations at a United Nations climate summit in promising to transition away from fossil fuels.

The oil and gas industry denounced the decision as a “win for Russia and a loss for American allies,” and argued that the gas shipments to Europe and Asia that have soared since Russia’s invasion of Ukraine are helping to displace coal.

“This is nothing more than a broken promise to U.S. allies, and it’s time for the administration to stop playing politics with global energy security,” said Mike Sommers, president of the American Petroleum Institute, a trade group.

Senator Bill Cassidy, Republican of Louisiana, whose state is home to multiple gas export terminals, said in a statement that “Putin must have designed this strategy.”

But this week, 100 European lawmakers wrote to Mr. Biden saying they would welcome a pause.

American gas, conservation and a build out of renewable energy has helped Europe avoid an energy crisis as it cut off the tap from Russia. “We are concerned that a false depiction of European energy needs is now being used as an excuse by the fossil fuel industry and their allies to dramatically expand U.S. L.N.G. exports to the global market,” the lawmakers wrote.

Exemptions would be made in cases of “unanticipated and immediate national security emergencies,” the president said.

Within the White House, there was little debate over the decision to delay CP2 because the United States is already shipping so much gas overseas, said people familiar with the discussions who asked not to be named because they were not authorized to speak publicly. That capacity is set to nearly double over the next four years, making the need for CP2 less urgent.

“Today, we have an evolving understanding of the market need for L.N.G., the long-term supply of L.N.G., and the perilous impacts of methane on our planet,” a fact sheet distributed by the White House said. “We also must adequately guard against risks to the health of our communities, especially frontline communities in the United States who disproportionately shoulder the burden of pollution from new export facilities.”

Climate activists celebrated the move, and canceled a protest they had planned for next week outside the Energy Department.

“The tide is turning,” said Colin Rees of Oil Change International, a group that seeks an end to fossil fuels. He called the pause “one of the most significant actions ever taken by a U.S. president to stop the dangerous expansion of fossil fuels and protect environmental justice.”

The review, which will be conducted by the National Laboratories, and a public comment period are expected to take months, almost certainly past the November presidential election.

Mr. Biden has an ambitious climate agenda but has typically shied away from attacking the fossil fuel industry. The rare exception was when gas prices soared after Russia’s invasion of Ukraine and the president castigated the industry for not producing enough oil while raking in record profits.

The announcement Friday hinted at a different tack, one welcomed by climate activists eager to see the president take on oil and gas companies.

“My administration will not be complacent,” Mr. Biden said. “We will not cede to special interests. We will heed the calls of young people and frontline communities who are using their voices to demand action from those with the power to act.”