The United States has heightened the readiness of some 8,500 troops in the United States amid tensions between Russia and Ukraine, but no decisions have been made yet to deploy them.

“Secretary Austin has placed a range of units in the United States on a heightened preparedness to deploy, which increases our readiness to provide forces if NATO should activate” the NATO National Response Force, said Pentagon press secretary John Kirby on Monday.

The NATO NRF is a multinational rapid response force comprised of land, air, maritime and Special Operations Force.

“The United States is deeply concerned about the current situation in Europe,” Kirby said. “We remain keenly focused on Russia’s unusual military activities near the Ukrainian border, including in Belarus, and consulting extensively with our transatlantic allies and partners. The department continues to support diplomatic efforts to deescalate the situation.