> Average American in 1984 couldn't conceive....
"Couldn't conceive" is pretty strong - it was the era of the Cold War, GI Joe, a hangover from the Cuban Missile Crisis, the contras. Maybe accurate to say the average American would find it highly improbable, and our eventual victory always assured because Chuck Norris, Rambo, and the inherent virtue of our cause against totalitarianism.
Anyway, I think the paratroopers that appear in Red Dawn are from Cuba or a socialist country in Central/South America, right? Which isn't terribly far-fetched in the context of the eighties imagination - maybe more accessible idea than a Soviet D-Day-style invasion. Also not out of line in history - didn't the Germans court the Mexicans in WWII? The French during the Civil War (I use the word "court" loosely with the French 'intervention', but hell, we got a holiday out of it).
The film was marketed saying that no foreign invasion of US soil had happened, though it ignored the Japanese invasion of Alaska. The "average American" probably still doesn't think of Alaska very often except for reality TV, much less its history.
https://www.archaeology.org/issues/433-2107/letter-from/9780...