(WASHINGTON) — 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.

“I want to be very clear about something. 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 added.

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 an 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 Poland and Germany, most to Poland.

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

Russian President Vladimir 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.

This a developing story. Please check back for updates.

Copyright © 2022, ABC Audio. All rights reserved.