My favorite Reagan soundcheck:
https://en.wikipedia.org/wiki/We_begin_bombing_in_five_minutes
[Prior to the speech, while the president was joking with the National Public Radio audio engineers during soundcheck, he riffed on his own speech, saying, “My fellow Americans, I’m pleased to tell you today that I’ve signed legislation that will outlaw Russia forever. We begin bombing in five minutes.”]
Note that he said Russia, not the Soviet Union. Perhaps he understood Richard Pipes’s basic insight that the problem was the Russian empire, not the “Communists” who hung on to the life-and-death power possessed by the feudal lords of old, but with new egalitarian-sounding titles.