Russians walk past security camera outside Sochi Winter Olympics Park

In this April 6, 2010 file photo, the Luzhniki Stadium which will be the venue of the World Athletics Championship scheduled for August 2013 in Moscow is shown. The organizers of the championship said on Tuesday, April 16, 2013, they will beef up security in the wake of deadly explosions at the finish line of the Boston Marathon. <AP Photo/Misha Japaridze, File>

People walk past a security camera installed outside the Olympic Park that is under construction for the the 2014 Winter Games, in the Black Sea resort of Sochi, Russia, Tuesday, April 16, 2013. Russian sports officials said Tuesday they will beef up security at sports events and the Sochi 2014 Winter Games in the wake of deadly explosions at Boston’s marathon that killed three people, and injured over 140 others. <AP Photo/Artur Lebedev>