Gas companies - and lobby groups who learned of the move ahead of the decision and unsuccessfully opposed it according to documents seen by Reuters - warned it would compromise global energy security and efforts to reduce carbon dioxide emissions.

The U.S. has become the biggest exporter of LNG to Europe, as EU countries have raced to replace Russian fuel following Moscow's invasion of Ukraine in 2022. Over 60% of U.S. LNG exports went to Europe in the last two years.

U.S. President Joe Biden last week paused approvals for applications to export from new LNG projects to review the climate change and economic impact of such projects.

A European Commission spokesperson told Reuters the U.S. decision "will not have any short-to-medium term impacts" on the EU's security of gas supply.

Europe has survived two winters without Russian pipeline gas, helped by lower heating demand due to mild weather and as high energy prices forced some industries to shut.

Even with new projects paused, the U.S. is set to expand its LNG capacity.

"There's a number of U.S. projects that are already under construction or that already have approval," said Jacob Mandel, Senior Associate at Aurora Energy Research.

U.S. LNG capacity will almost double to about 24.5 billion cubic feet per day (bcfd) by the end of 2028 if all of the approved projects are built.

Longer term, the European Union's gas consumption is expected to fall as the bloc shifts away from fossil fuels to meet climate change goals, so the region may not need the additional U.S. LNG - although strong demand growth elsewhere in the world means that LNG is likely to find a market.

"The EU will become a declining gas consuming region, the signals are downward," said Anne-Sophie Corbeau, a researcher at Columbia University's Center on Global Energy Policy.

"Between growing biomethane, Norwegian gas, some African gas, Azeri gas and declining production, we might just see eventually a progressive decline of our LNG demand, especially post 2030, and this is precisely for that period that the Biden decision would matter," she said.

A 'WORRYING' SIGNAL

Germany's gas importers SEFE and Uniper, Japan's top LNG buyer JERA and lobby groups have warned that the U.S. decision might compromise energy security worldwide.

SEFE and JERA plan to buy gas from Venture Global LNG's Calcasieu Pass 2 plant, one of the projects affected by the pause.

Please click here for a factbox on projects and gas deals that could be affected by the U.S. decision.

"The planned review could have negative consequences for Germany's and Europe's energy security in the future, for example in the form of price increases due to volume shortages on the market," said Germany's largest gas trader, Uniper.

U.S. energy firms in regions like the Permian might have to burn excess natural gas when producing oil if they have no outlet to sell it, thus adding to global warming, said a senior source at a major U.S. energy company.

"The decision ... could affect the trajectory and pace of the sector's growth and have potential to tighten the market in the long run," said Giles Farrer, head of gas and LNG asset research at Wood Mackenzie.

The International Gas Union, which has over 150 members, said the U.S. decision "is highly worrying...(and) will harm global energy security and emission reduction".

U.S. industry group LNG Allies urged Washington to allow the market to decide which new LNG projects should be built.

"Most energy outlooks expect global growth in LNG demand to continue well into the 2030s. If U.S. supply doesn't rise to meet that demand, will countries needing natural gas turn back to Russia? Or to coal?" a memorandum from LNG Allies said.