US President Joe Biden on Friday told reporters he plans to move troops to Eastern Europe “in the near term” as Russia amasses forces along the border, positioned for a possible invasion into Ukraine.

“I’ll be moving troops to Eastern Europe and the NATO countries in the near term — not a lot,” Biden told reporters after returning to Joint Base Andrews. The president’s comments come as the Pentagon says it has notified as many as 8,500 troops to standby for a potential deployment.

The President’s remarks were slightly stronger than those he made at the White House on Tuesday, when he revealed, “I may be moving some of those troops in the nearer term” to Europe.

The White House did not immediately respond to a request for comment when asked for more context on the president’s remarks.

The Pentagon placed 8,500 U.S. military personnel on heightened alert earlier this week for possible deployment, a move that came as NATO weighs a possible activation of its 40,000-strong response force to deter a Russian invasion.

Chair of the Joint Chiefs of Staff, Gen. Mark Milley told reporters at the Pentagon Friday that the troops have been authorized to “increase our readiness in the event we have to reinforce or assist our NATO allies. War is not inevitable.”

The bulk of new U.S. forces would join the NATO Response Force, both Pentagon and White House officials have said, but the number of countries they could deploy to is unclear.

Russia has amassed more than 100,000 troops along Ukraine’s border, and over the past week has started to deploy forces to neighboring Belarus for what it has described as military exercises.

The current Russian moves “feel[s] different in terms of what we’ve seen in the past,” Milley said Friday. “This is larger in scale and scope, and the massing of forces than anything we’ve seen in recent memory.”

Ukraine has a border with four NATO members — Poland, Slovakia, Hungary and Romania. Other alliance members in the north — Latvia, Estonia and Lithuania — have all indicated their willingness to base more U.S. troops.

On Friday, Defense Secretary Lloyd Austin spoke with the defense ministers of France and Germany — NATO allies who would play leading roles in any military buildup in the Baltic or in Eastern Europe — and called his counterparts in Poland and Romania earlier in the week.

Some U.S. forces have already been on the move. Six U.S. Air Force F-15 fighter jets normally based at the Lakenheath Air Force Base in the U.K. arrived in Estonia this week to bolster the Baltic Air Policing mission.

Any larger movement of ground troops would take days to muster and prepare to deploy from the U.S. Two Eastern European embassies confirmed to POLITICO on Friday that talks are underway on basing agreements, but said no decisions have been made.