Dagestan has become the center of an Islamic insurgency that has engulfed Russia's North Caucasus after two separatist wars in Chechnya. Militants seeking to create an independent state governed by Islamic Shariah law in the Caucasus launch daily attacks on police and other authorities there. One of the two ethnic Chechen brothers accused of staging the Boston Marathon bombings spent six months in Dagestan in 2012.
Andrei Soldatov, an independent Moscow-based security analyst, said the video threat need to be taken seriously.
"They have capabilities to strike beyond the North Caucasus, which they demonstrated in Volgograd," he said. "It's extremely difficult to stop a 'lone wolf' suicide bombing attack."<