Biden orders US troop deployments to reassure NATO allies amid Russia standoff

President Joe Biden has ordered U.S. troop deployments to reassure NATO allies amid the standoff with Russia over Ukraine.

Pentagon press secretary John Kirby announced the imminent arrival of several thousand U.S. troops -- some already in Europe and some from the U.S. -- to NATO allies in eastern Europe at a Pentagon briefing Wednesday -- the first major movement of U.S. forces in response to concerns Russia will invade Ukraine.

"President Biden has been clear that the United States will respond to the growing threat to Europe's security and stability. Our commitment to NATO Article 5 and collective defense remains ironclad. As part of this commitment and to be prepared for a range of contingencies, the United States will soon move additional forces to Romania, Poland, and Germany," Kirby said.

All of the troops would be under U.S. command.

In a brief exchange with reporters Wednesday afternoon, President Joe Biden said the move was “totally consistent with what I told Putin in the beginning."

"As long as he is acting aggressively," Biden said, "we're going to make sure we can reassure our NATO allies and Eastern Europe that we're there and Article Five is a sacred obligation.”

Russia called the deployments “destructive.”

"Destructive steps that are unjustified by anyone, they increase military tension and narrow the room for political decisions,” Russia’s deputy foreign minister, Alexander Grushko, said, according to the Russian news agency Interfax.

The White House said the deployments were not in response to any specific, recent event.

"I would not read this as a decision made based on any events over the last 48 hours or a couple of days," White House press secretary Jen Psaki said Wednesday. "We've been in discussion and under discussion with our partners and allies in the region where these troops are going for several weeks now.”

Psaki said the United States was aiming to reassure allies, deter Russia and "ensure we are ready for every contingency."

Kirby said he wanted to "be very clear" that "these are not permanent moves."

"They are moved designed to respond to the current security environment. Moreover, these forces are not going to fight in Ukraine. They are going to ensure the robust defense of our NATO allies," he said.

A senior defense official had earlier confirmed to ABC News that about 3,000 U.S. troops will be given orders to deploy to Europe or, if they're already in Europe, to head to countries in eastern Europe.

One of the units moving into eastern Europe from Germany is a fast-moving armored Stryker unit.

"It's important that we send a strong signal to Mr. Putin and frankly, to the world that NATO matters to the United States. It matters to our allies, and we have ironclad Article 5 commitments attack on one is an attack on all," Kirby said.

The troop movements are separate from the 8,500 U.S. troops put on "heightened alert" to reinforce NATO's Response Force if needed -- and none would go to Ukraine.

Pressed on what signal it sends that the U.S. is not waiting for a NATO vote to deploy an alliance force, Kirby said "the signal that sends -- that we're that we're moving additional U.S. forces into allied territory, at the request and with the invitation of those countries -- is that we take our NATO commitments very, very seriously."

Kirby said 1,000 soldiers based in Germany will arrive in Romania in "the coming days" at the request of the country, augmenting the roughly 900 U.S. troops already in Romania.

Another 2,000 troops from Fort Bragg in North Carolina will deploy to Europe, with 1,700 heading to Germany and about 300 to Poland, the White House said.

"The 82nd Airborne Division is deploying components of an Infantry Brigade Combat Team and key enablers to Poland. And the 18th Airborne Corps is moving a joint task force capable headquarters to Germany. Both of them, as you know, are based in Fort Bragg, North Carolina," Kirby said.

The Pentagon spokesperson said that these moves could be "preliminary," meaning more troops could be sent. He added that the 1,000 troops heading to Romania will be joining the country's own "very capable" military, and will also be joined by an unspecified number of French troops.

Asked why the deployment is coming now, Kirby blamed Russian President Vladimir Putin who, he said, "continues to add forces -- combined arms, offensive capabilities even over just the last 24 hours."

"He has showed no signs of being interested or willing to de-escalate the tensions," Kirby said of the Russian leader.

After last week saying the U.S. thought a Russian invasion was “imminent,” Psaki said Wednesday she no longer would use that word.

Ukrainian officials had publicly disputed the fact that a Russian attack was “imminent” and even criticized the Biden administration for how it was describing the threat.

A better way to describe the White House’s view about what Putin may do, Psaki said Wednesday, was that “he could invade at any time.”

The U.S. still believes Putin has not made a decision about how to proceed, she said.

Kirby emphasized the Biden administration does not believe conflict is inevitable.

The announcement comes after Biden told reporters on Friday that he would be moving American forces "in the near term."

Putin blamed the escalating tensions on the U.S. and the West for having "ignored" Russia's key demand that NATO bar Ukraine from joining the organization. The U.S. and NATO allies argue Russia is the aggressor, having already invaded Crimea and massing troops at the border.

ABC News' Ben Gittleson and Max Karmen contributed reporting.