The official story from the Left:

The U.S.S.R. was this impotent, harmless bear, broke and broken, ready to fall apart at a touch. They only built up their military because of their fear of our aggressive approach. Any information about their weapons, plans, or worldwide strategies of conquest were just exaggerated lies generated by the U.S. military/industrial complex to keep the defense funds flowing.

If we had unilaterally disarmed, the Soviet Union would have joyfully followed suit. A golden opportunity lost by jingoistic U.S. administrations.

The collapse of the Soviet Union was utterly spontaneous, and had nothing to do with the actions of any particular U.S. administration.

Take notes. There'll be a test later. ;)