Washington's announcement comes after NATO said it was placing troops on standby and reinforcing eastern Europe with more ships and fighter jets, in what Moscow denounced as an escalation of tensions.

A pair of Tu-95 strategic bombers of the Russian air force are parked at an airbase in Engels near the Volga River in Russia on January 24, 2022.
A pair of Tu-95 strategic bombers of the Russian air force are parked at an airbase in Engels near the Volga River in Russia on January 24, 2022. (AP)

At President Biden's direction, the Pentagon has placed about 8,500 US-based troops on "heightened alert" for potential deployment to Europe amid rising fears of a possible Russian military move on Ukraine.

Pentagon press secretary John Kirby said on Monday no final decisions had been made on deployments, which he said would happen only if the NATO alliance decides to activate a rapid-response force "or if other situations develop" in connection with tensions over Russia’s military buildup along Ukraine’s borders.

"What this is about is reassurance to our NATO allies," Kirby said, adding that no troops are intended for deployment to Ukraine itself.

Kirby said Defense Secretary Lloyd Austin recommended to Biden that up to 8,500 troops be ordered to prepare for potential deployment to Europe in light of signs that Russian President Vladimir Putin is not de-escalating his military pressure on Ukraine. 

Kirby said he was not prepared to identify the US-based units because they were still being notified.

READ MORE: NATO deploys ships, jets to eastern Europe in Ukraine crisis

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Biden to speak with EU leaders 

Later Monday, Biden was to hold a video call with several European leaders on the Russian military buildup and potential responses to an invasion, the White House said.

The Pentagon’s move comes as tensions have soared between Russia and the West over concerns that Moscow is planning to invade Ukraine, with NATO outlining potential troop and ship deployments, Britain saying it would withdraw some diplomats from Kiev, and Ireland denouncing upcoming Russian war games off its coast.

Prior to the US announcement, the Western alliance's statement summed up moves already described by member countries, but restating them under the NATO banner appeared aimed at showing resolve. 

The West is ramping up its rhetoric in the information war that has accompanied the Ukraine standoff.

Russia has massed an estimated 100,000 troops near Ukraine's border, demanding that NATO promise it will never allow Ukraine to join and that other actions, such as stationing alliance troops in former Soviet bloc countries, be curtailed. 

Some of these, like any pledge to permanently bar Ukraine, are non-starters for NATO — creating a deadlock that many fear can only end in war.

READ MORE: ‘No minor incursion’: Biden clarifies comments on Russia, Ukraine tensions

NATO bolstering 'deterrence'

Russia denies it is planning an invasion and says the Western accusations are merely a cover for NATO's own planned provocations. Recent days have seen high-stakes diplomacy that failed to reach any breakthrough and maneuvering on both sides.

NATO said on Monday it is bolstering its "deterrence" in the Baltic Sea region. Denmark is sending a frigate and deploying F-16 warplanes to Lithuania; Spain is sending four fighter jets to Bulgaria and three ships to the Black Sea to join NATO naval forces, and France stands ready to send troops to Romania. The Netherlands also plans to send two F-35 fighter aircraft to Bulgaria from April.

The West is nervously watching Russian troop movements and war games in Belarus for any signs of an invasion. Russia has already invaded Ukraine once, annexing the Crimean Peninsula in 2014. 

It also supported pro-Russian Ukrainian separatists fighting the Kiev government in the country's eastern region known as the Donbass. About 14,000 people have been killed in the conflict.

READ MORE: EU plans to back Ukraine with $1.36 billion aid package

Source: AP