The 3rd Armored Brigade Combat Team, 4th Infantry Division, from Fort Carson, Colo., has begun moving into Poland as part of the biggest U.S. military deployment in Europe since the end of the Cold War.
It's part of an Obama administration effort to deter perceived growing Russian aggression in Eastern Europe. The Kremlin isn't happy.
"These actions threaten our interests, our security," President Vladimir Putin's spokesman Dmitry Peskov said. "Especially as it concerns a third party building up its military presence near our borders. It's not even a European state."