In 1979, a rare outbreak of anthrax disease in the city of Sverdlovsk killed nearly 70 people. The Soviet government publicly blamed contaminated meat, but U.S. intelligence sources suspected the outbreak was linked to secret weapons work at a nearby army lab.
In 1992, Russia allowed a U.S. team to visit Sverdlovsk. The team's investigation turned up telltale evidence in the lungs of victims that many died from inhalation anthrax, undoubtedly caused by the accidental release of aerosolized anthrax spores from the military base. Given the hundreds of tons of anthrax the Sverdlovsk facility could produce, the release of just a small amount of spores was fortunate.
News of the immensity of the Soviets' biological weapons program began to reach the West in 1989, when biologist Vladimir Pasechnik defected to Britain. The stories he told—of genetically altered "superplague," antibiotic-resistant anthrax, and long-range missiles designed to spread disease—were later confirmed by other defectors who had worked in the Soviet program, including Ken Alibek and Sergei Popov.
The Soviet program was spread over dozens of facilities and involved tens of thousands of specialists. In the late 1980s and 1990s, many of these scientists became free agents, and while there is no evidence that any went on to work on nefarious projects, the potential remains.