U.S. troops in Poland are preparing to help American citizens who may flee to the country if Russia invades Ukraine, U.S. officials said Wednesday.

The officials, speaking on the condition of anonymity, said the troops would not enter Ukraine to evacuate American citizens but would set up temporary facilities within Poland if needed.

The Pentagon has said that around 1,700 service members, mainly from the 82nd Airborne Division, are deploying from Fort Bragg, North Carolina, to Poland.

Russia has denied plans to invade Ukraine but has deployed more than 100,000 troops near Ukraine's borders and says it could take unspecified military measures if its demands are not met, including a promise by NATO never to admit Ukraine.

The officials said the plan had been approved by the White House and was part of prudent planning. The approval was first reported by the Wall Street Journal.

A White House official said that the U.S. was not planning for a mass evacuation of American citizens from Ukraine.

"We are constantly evaluating the evolving security situation and planning for a range of contingencies as we always do," the official said.

President Joe Biden said this week it would be wise for Americans to leave Ukraine.

Unlike the messy evacuation of U.S. citizens from Afghanistan last year, officials said people should be able to drive to Poland from Ukraine.