Unidentified masked individuals hold a Russian flag as they block the Trade Union building in Semferopol, the administrative center of Crimea, on March 1, 2014. Russia's parliament on March 1 gave President Vladimir Putin the go-ahead to send troops into Ukraine, despite a warning from Washington that such a deployment would results in "costs" for Moscow. The stark escalation of the ex-Soviet country's three-month political crisis came amid growing instability in Ukraine's predominantly Russian peninsula of Crimea that has housed Kremlin navies for nearly 250 years. AFP PHOTO/ GENYA SAVILOV