The possible deployment could involve 1,000 to 5,000 troops, along with naval vessels and aircraft, according to the New York Times.

It said the number could rise sharply if conditions deteriorate.

CNN said the Pentagon is identifying which units would go but that the final decision to deploy them has not been taken.

The option came out of discussions on the Ukraine crisis between US President Joe Biden and his advisors, including Defense Secretary Lloyd Austin, over the weekend.

US officials, speaking anonymously, said that they are consulting with allies on deployments and studying all scenarios.

NATO said Monday it was sending jets and ships to bolster its eastern European flank. The United States, Britain and Australia has ordered diplomats' families to leave Kyiv.

The moves came after talks between Russia and the US-European side last week failed to bring about any significant breakthrough.

Russia has an estimated 100,000-plus troops on the Ukraine border and is demanding guarantees that the country would not be allowed to join NATO, which Kyiv has repeatedly asked to do.

The US and NATO allies have warned Moscow of tough sanctions and other actions that would cause "severe" damage to the Russian economy if it invades Ukraine.