Daniel Treisman offers an ingenious explanation for the fact that the Russian Federation held together after the collapse of the Soviet regime. Unlike the three other ethnic federa- tions in the communist world-Yugoslavia, Czechoslovakia, and the USSR itself-the Russian Federation, which was the largest of the 15 nationally based constituent republics in the Soviet Union, avoided disintegration. Many observers in the early 1990s feared the same pressures that had led to powerful separatist movements among the Soviet republics would prove too strong for the fragile central government to resist. Yet, Russia managed to maintain itself as a federal state, albeit weak. The one constituent republic in which separatism ultimately led to armed confrontation was Chech- nia, where a brutal war began in 1994, paused in 1996, and erupted again in 1999.