Plutonium has been closely regulated since the discovery of the Atomic Bomb. Any nation that has access to purified plutonium and the "secret" of radiation pressure can create the Hydrogen Bomb.
The Kerr-McGee Nuclear Corporation was smuggling plutonium out of their own plant in 1974 when they were found out by Karen Silkwood. She was run off of the road before she could meet with a New York Times reporter and hand over the evidence she was carrying in a manila folder. The Oklahoma highway patrol arrived on the scene and the manila folder disappeared. She also had evidence of Kerr-McGee making faulty fast breeder reactor rods. The missing plutonium was being smuggled out of the country with the help of the CIA to South Africa. This information was enough to warrant her death. She was being poisoned by plutonium salted on her food but they couldn't wait for that to take effect.