TWO bomb attacks in the southern city of Volgograd within 24 hours have killed more than 30 people, injured over 100 and brought the city once known as Stalingrad into a state of terror. The latest bomb, the third in three months, ripped through a trolley-bus in the morning rush-hour, killing at least 14 people. This came less than a day after a bomb went off at a railway station—one of the most closely guarded places in the city—killing 17 people. Both explosions appear to have been set off by suicide bombers. Although nobody has claimed responsibility, the attacks are most likely the work of Islamist fundamentalists from the North Caucasus.



Coming just six weeks before Russia’s winter Olympics in Sochi, only a few hundred miles from the North Caucasus, the attacks bear out a threat made by Doku Umarov, the self-proclaimed emir of the North Caucasus and the leader of a terrorist group. In July Mr Umarov called on his followers to use all means possible to disrupt the Olympic games, and lifted a moratorium on attacking civilian targets on Russian territory which had been in place since December 2011’s anti-government protests in Moscow. The coordinated attacks suggest that a well organised cell is operating in Volgograd, one of the main transport hubs in the south of Russia and a symbol of Soviet resistance during the second world war.



In October a female suicide bomber from Dagestan in the North Caucasus set off a bomb on a Moscow-bound bus, killing six people. Less than a month later her ethnically Russian husband and four other militants were killed in a stand-off with security services. The attack on the railway station on December 29th appears to have been carried out by a Russian man identified as Pavel Pechenkin, who converted to Islam and was linked to one of the North Caucasus terrorist groups.



Ekaterina Sokiryanskaya, a Caucasus expert at International Crisis Group (ICG), a think-tank, says the latest attacks illustrate a new trend in the way the terrorists operate. Whereas a few years ago most suicide bombings were carried out by Chechen women seeking to avenge their killed relatives, the recent bombings are the work of ideologically motivated jihadists from the neighboring Dagestan—some of them ethnic-Russian men—who are harder to identify and detect than women in headscarves.



Terrorism stemming from the nearly two-decade-long conflict in the North Caucasus has been one of the main concerns about Sochi, a Black Sea coast city which is only 300 miles (480km) from the scene of the deadliest conflict in Europe. A recent report by ICG says at least 700 people died in the conflict in 2012, with as many Russian soldiers dead as America has lost in Afghanistan. Dagestan, the largest and most ethnically complex of all the North Caucasus republics, has been particularly violent.



Ms Sokiryanskaya says that in preparation for the Sochi Olympics the Russian security services have brutally clamped down on any form of legal activity by Salafists, who follow a fundamentalist form of Islam. Their mosques and schools have been closed down and their spiritual leaders harassed. All this has only led to their further radicalisation. Vladimir Putin, Russia’s president, who came to power on the wave of the second war in Chechnya in 1999, has rolled back much of the region’s autonomy and clamped down on Russia’s political freedoms in the name of fighting terrorism, but he has failed to resolve the root of the conflict. Mr Putin made no public statement on the bombings but dispatched Alexander Bortnikov, the head of the security service, to Volgograd. The latest double-attack is the most audacious yet, but may not be the last one before the winter Olympics begin in February.