Simferopol, Ukraine (CNN) -- [Breaking News Update, 10:02 a.m. ET] (CNN) -- Russia's upper house of parliament voted Saturday to approve the use of military force in Ukraine. The vote was unanimous. [Original Story, published 9:23 a.m. ET] (CNN) -- Russian President Vladimir Putin has asked the upper house of parliament for approval to send Russian troops into Ukraine's Crimea region to normalize the political situation there, the Kremlin said Saturday. Due to the "extraordinary situation in Ukraine," Putin said, there are threats to the lives of Russian citizens and Russian military personnel based in the southern Crimean region. It comes on the same day that the new pro-Russian leader of Crimea, Sergey Aksyonov, asked Putin for help in maintaining peace in the Black Sea peninsula -- where Russia has a major naval base at Sevastopol. International concerns are mounting that Moscow may intervene militarily in the crisis, despite warnings from the United States and other Western powers that it should respect Ukrainian sovereignty. In response to Putin's move, Swedish Foreign Minister Carl Bildt tweeted: "Russian military intervention in Ukraine is clearly against international law and principles of European security." The newly appointed interim government in the Ukrainian capital, Kiev, is seeking to prevent tensions in Crimea, which has a majority-Russian population, escalating into a full-blown bid for separation. Ukraine suspects Russia of fomenting separatist tensions in the autonomous region. Amid the uncertainty, about 300 gunmen wearing Russian Special Forces uniforms attempted to take over the Sevastopol unit of the Ukrainian Coast Guard, a senior official with the Ukrainian Border Service said Saturday. The gunmen were positioned outside the Ukrainian Coast Guard building, with local residents standing between the two sides, said Col. Sergii Astakhov, assistant to the chief of the Ukrainian Border Service. The residents are reportedly trying to negotiate and asking the gunmen not to attack, Astakhov said. Meanwhile, the Ukrainian Coast Guard has moved its ships away from the immediate coastline, and they are being approached by three motorboats and one cruiser from the Russian Black Sea Fleet, Astakhov said.