The following CNN news video is about security measures for the Sochi Winter Olympics, which are coming up very fast in February of 2014. In light of the recent Boston Marathon bombings and other events, there is an increased concern about antiterror security procedures for the Sochi Games. The Tsarnaevs are from Russia, and there are definitely some domestic threats to safety at the upcoming Sochi Olympics. This video was added to the CNN website on May 13, 2013.
Some of the measures seen here for an event at the Sochi ice rink include scanning of all buses. There is a humongous scanner that goes over the top of the bus. In addition, before entering the rink, all people are checked in the same way you are checked before boarding an airplane. That can include the usual patdowns, as well. Another thing Sochi will be using is a network of CCTV cameras that is supposed to be able to monitor crowd behavior for suspicious activity.
The North Caucusus are about 500 kilometers from Sochi. There is an Islamic insurgency there. This is the area where the Tsarnaevs originated from (Chechnya is in this area).
Vadim Mukhanov is a Caucusus expert. He says the close proximity to the insurgency increases the risk of a terrorist attack at the Sochi Olympics.
Russia says it was already taking security and terrorism concerns seriously even before the Boston Marathon bombing.