Watch: Putin threatens to use nuclear weapons. "It's not a bluff."

In a televised address today, Russian Prime Minister Vladimir Putin announced a mobilization of troopsits first since World War IIand threatened the use of nuclear weapons in defense of Russian. "I'm not bluffing," he said. Video above. From The Guardian:

The Russian leader's televised address to the nation comes a day after Russian-controlled regions in eastern and southern Ukraine announced plans to hold "referendums" this weekend on becoming part of Russia.