On Thursday morning three gunmen opened fire on the head of the special task force police unit in the capital of the Republic of Dagestan. The officer died on the way to hospital.
Look at a map of the North Causcasus region. Lots of small countries, lots of recent border changes, lots of old Soviet military weapons and gear, religious and political dissidents, and a weakened, but resurgent Empire looking to prove its strength and assure hegemony. Its going to get worse from here. Don't forget ethnic rivalries, mineral deposits, and oil. More food for the fire.
And another thing: this is not the "War against Terror" that the West is fighting. Don't assume they are the same because they are similar. Many in the Kremlin could not have been happier on 9/11, because they knew that they could cast their regional wars in the light of terrorism from now on and the West would not trouble them. The same holds true for China and their restive Muslim population, the Uyghurs. Russia and the Soviet Union have been fighting in this area for well, ever since they got there. Gangs, Muslim fanatics, Drug smugglers, former soldiers, warlords. They got it all.