Officials say a new video promises a terror attack at the Olympic Games in Sochi, which are only weeks away.

Militant group Vilayat Dagestan posted a message and a video on a well-known jihad website in which it claims responsibility for the back-to-back suicide bombings in Volgograd.

The threat includes a promise to attack the Olympic Games. "We've prepared a present for you and all tourists who'll come," the video says. "You will get a present from us for the Muslim blood that's been spilled."

Russian President Vladimir Putin has promised visitors will be safe. Putin pointed to the G-20 summit as an example of Russia's experience providing security for international events.