The scene of the second bomb blast. Photo: Screenshot.

New York Times – MOSCOW — A deadly suicide bombing at a crowded railroad station in southern Russia on Sunday, followed by a blast in a trolley bus on Monday in the same city, raised the specter of a new wave of terrorism just six weeks before the Winter Olympics in Sochi.

President Vladimir V. Putin’s government has worked to protect the Olympics with some of the most extensive security measures ever imposed for the Games. But the bombings, in Volgograd, underscored the threat the country faces from a radical Islamic insurgency in the North Caucasus that has periodically spilled into the Russian heartland, with deadly results, including several recent attacks.

Read full story.