A soldier guards the Volgograd main railway station in Volgograd, Russia early Monday, Dec. 30, 2013. A bomb blast tore through a trolleybus in the city of Volgograd on Monday morning, killing at least 10 people a day after a suicide bombing that killed at least 17 at the city's main railway station. Volgograd is about 650 kilometers (400 miles) northeast of Sochi, where the Olympics are to be held. (AP Photo/Denis Tyrin)The suicide bombings in Russia serve as a chilling reminder of what the Wintry weather Olympics symbolize to terrorists: A high-profile target with more than 2,500 athletes, some of them world-famous, waving the flags of nearly 90 international locations.