U.S. military to be on standby

— -- Amid the recent security and terrorist concerns involving the Sochi Olympics, the U.S. is preparing a contingency plan to keep American athletes and officials safe.

The U.S. military will have warships and several aircraft on standby during the Games, CNN reports, citing a U.S. official with knowledge of the plans, adding that Moscow would first need to ask for help before any American action was taken.

Still, the ships are in place "if something happens like a major terrorist attack and we need to get Americans out," the official told CNN.

Russia's counterterrorism agency is studying a video posted by an Islamic militant group that asserted responsibility for suicide bombings that killed 34 people last month and is threatening to strike during the Games.

The video was posted online Sunday by a militant group in Dagestan, a predominantly Muslim republic in Russia's volatile North Caucasus. The Olympic host city of Sochi lies 300 miles west of Dagestan.

Russia has responded to the Islamic threat by introducing some of the most sweeping security measures ever seen at an international sports event. Some 100,000 police, army and other security forces have been deployed, according to analysts, and tight restrictions have been placed on access to the Sochi area.

Anyone attending the Winter Olympics has to buy a ticket online from the organizers and obtain a spectator pass that requires providing passport details.

Authorities have already barred access to all cars registered outside of Sochi, and Russian police have gone house-to-house methodically screening all city residents.

Information from The Associated Press was used in this report.