US President Joe Biden's administration on Tuesday said it was looking at ways of shoring up energy supplies to Europe if Russia were to invade Ukraine.
The EU depends on Russia for about a third of its gas supplies. Any interruption to Russian supplies to Europe would exacerbate an energy crisis caused by shortages.
Senior Biden administration officials said the US was in talks with major energy-producing countries and companies around the world over a possible diversion of supplies to Europe if Russia invaded.
The officials did not name the countries or companies involved in discussions but said they included a broad range of suppliers, including sellers of liquefied natural gas.
"We've been working to identify additional volumes of non-Russian natural gas from various areas of the world; from North Africa and the Middle East to Asia and the United States," a senior administration official said.
"Correspondingly, we're ... in discussions with major natural gas producers around the globe to understand their capacity and willingness to temporarily surge natural gas output and to allocate these volumes to European buyers."
Tensions remain high after Nato said on Monday that it was putting forces on standby and reinforcing Eastern Europe with more ships and fighter jets in response to a Russian troop build-up near its border with Ukraine.
The Pentagon has said up to 8,500 US troops are now on "heightened alert" status and will be ready to be moved by the end of the week.
"I may be moving some of those troops in the near term, just because it takes time," Mr Biden said on Tuesday.
But he said that American soldiers would not sent to Ukraine.
"We have no intention of putting American forces or Nato forces in Ukraine," Mr Biden said. "There is not going to be any American forces moving into Ukraine."
The US president also said he was considering a rare move in imposing personal sanctions on Russian President Vladimir Putin if he chose to invade Ukraine, as one of the "severe consequences" the US had warned about.
Mr Biden did not elaborate, but US legislators want him to impose sanctions on many in Mr Putin's inner circle.
That includes his family and a woman reported to be the president's romantic interest.
Many western nations expect Mr Putin to direct his forces to enter Ukraine. The US estimates there are 127,000 Russian troops on Ukraine's borders.
"It would be the largest invasion since World War II," Mr Biden said. "It would change the world."
Agencies contributed to this report.