I did not know this:

According to senior SVR officer Sergei Tretyakov, the KGB was responsible for creating the entire nuclear winter story to stop the Pershing missiles. Tretyakov says that from 1979 the KGB wanted to prevent the United States from deploying the missiles in Western Europe and that, directed by Yuri Andropov, they distributed disinformation, based on a faked a "doomsday report" by the Soviet Academy of Sciences about the effect of nuclear war on climate, to peace groups, the environmental movement and the journal AMBIO.

Wikipedia is of two minds about this. Knowing of other nasty stuff accomplished by the KGB, it’s entirely easy to believe the latter.