Two suicide attacks have been carried out on the Moscow underground. Dozens of people have been reported killed. It's believed the bombers were women, and suspicion has already fallen on Chechen terrorists.
The choice of one of the targets in particular is significant. One of the explosions hit the station underneath the Lubyanka, the infamous former home of the Soviet secret service, the KGB, and still used by its successor, the FSB. The message from whoever was behind the attacks is clear enough. Nowhere in Russia, not even important buildings belonging to the central government, is safe.
There are plenty of reasons for assuming this is the work of the Chechens. First, women were involved, as they were in attacks on the Moscow underground and two airliners back in 2004 (around the same time as the Beslan Massacre). Those incidents were blamed on the so-called 'Black Widows' of Chechen soldiers killed fighting the Russians. Also, the Russian military has recently had a series of succeses in its campaign against Islamic separatists fighting in Chechnya and nearby republics, so it was a timely moment for the rebels to show they're still capable of striking back. One of the main websites used by Chechens, Kavkaz Center, is already repeating a familiar allegation, that the attacks were in fact false flag operations carried out by the Russian security services themselves.
As for what happens next, history tells us the Chechens will probably have more spectacular attacks planned. Despite the inevitable tightening of security across Russia, the country and its transport infrastructure is so vast, it will be almost impossible for the Kremlin to protect every possible target. Instead, expect President Medvedev and Prime Minister Putin to order high-profile military retaliations in and around Chechnya, to shore up both public confidence, and their own reputations.