Actually from what i have seen, they were somewhat irrational and paranoid around that time, , with Yuri Andropov bluntly announcing that the United States was preparing a secret nuclear attack on the USSR, and looking for anything that would confirm it.
http://en.wikipedia.org/wiki/Able_Archer_83
Now the irrational and paranoid reside in the democratic party.
It was incorrect, but they were basing their beliefs on our actions. Yes, they did believe that we might launch a preemptive attack, but isn't that exactly what our own and western European media and "intelligentsia" was saying as well? That Reagan was a cowboy?