Russia has withdrawn from the Treaty on Conventional Forces in Europe (CFE), meaning its now free to place as many tanks, troops, and other military equipment in the European theatre as it pleases. According to the Kremlin, the action was taken due to "extraordinary circumstances ... which affect the security of the Russian Federation and require immediate measures."
They've threatened this for quite some time now, always because of the European missile shield. Of course, they've also made all sorts of contradictory statements about accepting the shield, participating in it, and even providing the principal radar installations. And so, one wonders what "extraordinary circumstances...require immediate measures."
Things continue to get interesting. It's like the Chinese curse, "May you live in interesting times." I'm afraid we do.