Summary Successive-day bombings in Russia exposed Olympic security threat.
MOSCOW (AFP) - Successive-day bombings on a railway station and trolleybus in Russia's heartland expose the challenge President Vladimir Putin faces in ensuring a safe Olympics on the edge of the violence-plagued North Caucasus.
The Kremlin chief beat extreme odds in 2007 to bring the showcase winter event to the summer Black Sea retreat of Sochi after personally pledging before Olympic chiefs in Guatemala to make the Games into a "safe, enjoyable and memorable experience".
Russia has since poured more than $50 billion into an event that has become linked inextricably with Putin's image as a strongman fighting to restore the superpower status his nation enjoyed in Soviet times.
But Putin's 14-year rule has also been tied to North Caucasus conflicts that began in Chechnya and have since spread across the mostly-Muslim region that Islamists want to turn into their own state.
Russia is already imposing a "limited access" cordon around Sochi from January 7 to keep non-resident cars from coming anywhere near the Olympic venue.
Extra measures are also being taken to monitor local Internet and cellphone network traffic that could herald the plotting of still new attacks.
Yet the twin blasts in Volgograd -- a million-strong city revered by Russians for enduring the epic World War II Battle of Stalingrad -- show that strikes do not have to target Sochi directly to set off Olympic alarms.
"They tried to deal a blow to Sochi," Volgograd's parliament representative Mikhail Markelov said as the combined death toll from both attacks climbed to 31.
"This was a serious intimidation attempt."
