MOSCOW (AP) — An Islamic militant group in Russia's North Caucasus has claimed responsibility for twin suicide bombings in the southern city of Volgograd last month and posted a video threatening to strike the 2014 Winter Olympics in Sochi. There had been no previous claim of responsibility for the bombings, which killed 34 people and heightened security fears before next month's Olympics. In the video, two Russian-speaking men sitting in front of black banners with Arabic verses warn President Vladimir Putin that if the games are held, "we will give you a present for the innocent Muslim blood being spilled all around the world." They add that "for the tourists who come there will be a present, too." The video was posted Sunday on the website of the militant group Vilayat Dagestan. There's been no reaction to the video from the Russian security services but In response to the terrorist threat, Russia has introduced sweeping security measures for the Sochi Games.