File photo from the Associated Press shows soldiers from NATO countries attending military exercises in Lithuania.

US President Joe Biden is considering deploying thousands of troops, as well as warships and aircraft, to Eastern Europe and the Baltic States as part of a broader effort to bolster NATO allies amid allegations that a Russian incursion into Ukraine could be imminent.

The move, which will be regarded as extremely provoking by Russia, was discussed during a weekend meeting at Camp David, the presidential retreat in Maryland, during which Pentagon officials and security advisers presented Biden with several options to respond to what they describe as Russian aggressive moves on the border with Ukraine.

The options under discussion include sending between 1,000 to 5,000 troops to NATO countries including Latvia, Lithuania, Estonia, and Poland, in what would amount to a dramatic shift of American assets much closer to Russian doorstep, The New York Times reported on Sunday.

But officials told the Times that the possibility of sending US troops to Ukraine itself, which is not a NATO member, remained off the table.

President Biden is also considering deploying naval vessels to make port visits to NATO allies unnerved by the Russian moves.

Senior administration officials with knowledge of the Camp David meeting said on Sunday that other courses of action discussed include sending bomber flights over the region and moving some military assets from Europe to allied countries near Ukraine.

Even as we�re engaged in diplomacy, we are very much focused on building up defense, building up deterrence, Secretary of State Antony Blinken said in an interview that aired Sunday on CBS. NATO itself will continue to be reinforced in a significant way if Russia commits renewed acts of aggression. All of that is on the table.

In an interview with CNN on Sunday, Blinken said a swift, a severe and a united response from the US and Europe would follow if a single additional Russian force goes into Ukraine in an aggressive way.

NATO allies may also contribute troops to amplify what Washington hopes would be a gesture of unity among the fractured military alliance and a warning to Russia, which they have accused of amassing more than 100,000 troops and weaponry on the border with Ukraine in preparation for an invasion.

NATO announced on Monday that allied countries were dispatching more ships and fighter jets to Eastern Europe. The alliance also pointed to reports that the US is considering deploying troops.

The United States has also made clear that it is considering increasing its military presence in the eastern part of the alliance, NATO said in a statement.

Russia says it has no intention of moving into Ukraine, and that it can freely move troops around within its territory as a response to NATO�s eastward expansion. Russia has demanded legally binding guarantees from NATO that it will halt its eastward expansion and return to its 1997 borders. It also demands that the military alliance rule out admitting Ukraine as a member.

Commenting on the Times reporting, senior Russian lawmaker Andrei Kartapolov told the Interfax news agency on Monday that Moscow would respond appropriately if the United States deployed more troops in Eastern Europe and the Baltic countries.

Deploying military personnel and hardware would signal a major pivot for the Biden administration, which has projected a degree of reluctance to enter another conflict following America�s humiliating exit from Afghanistan.

Senior US and Russia officials have engaged in diplomatic discussions for days in the hope of deescalating the situation. However, with talks stalled, the Biden administration appears to be shifting from its more restrained approach, officials said.

The US and its European allies currently provide military support for Ukraine. They have been harping on about what they call Russia�s ill-intentioned plans for Ukraine since 2014, when a wave of protests overthrew the country�s democratically-elected and pro-Moscow government and replaced it with a Western-leaning administration.

Relations between Russia and the West have soured since 2014, when the then Ukrainian territory of Crimea voted in a referendum to rejoin the Russian Federation. Kiev refused to recognize the results, and later imposed sanctions on Moscow.

Ukraine and its Western allies accuse Russia of stoking conflict between Ukrainian soldiers and ethnic Russians in the Donbass region. Moscow denies the allegation.

The Kremlin said on Monday that the Western narrative about the situation in Ukraine was marked with hysteria and laced with lies, warning that the possibility of a military confrontation in eastern Ukraine, initiated by Kiev, was higher than ever.