As the city slept, the truck and its armed escorts slipped away from the reactor, at a Czech Technical University campus on the outskirts of the city, and passed through deserted streets, stopping at last near a runway at the capital's airport. Soon a Russian cargo plane landed to carry the uranium to a more secure storage center in Russia.

The nuclear reactor at the campus, which for 15 years had stored nuclear material in a lightly guarded setting, was now free of a fuel that terrorists might covet. As the cargo plane's rear hatch locked shut, a team of American nonproliferation officials watched with approval.