“...I remember wondering what business the Cubans could possibly have invading the US...”
Given that Cuba was a Soviet client state I’m sure their armed forces would have done something in support of a Soviet attack upon the US.
I remember a scene in the Chuck Norris movie “Invasion U.S.A.” where “terrorists” dress up as policemen and open fire on a crowd of hispanics (IIRC), thereby starting a violent beef between the locals and the real police. I don’t doubt that something similar could have been in the works. The Cubans did have commando and specops units that would no doubt have been placed under the command of the GRU.
Now, why the Cubans ended up in Colorado in the movie is a whole ‘nother thing, unless they were already in Mexico causing trouble and just advanced north into Aztlan territory.
Just my 2 cents.
Remember in the opening sequence we’re informed that Mexico and Central America have gone commie and invited the Russkies in, along with their Cuban allies so that’s where the invasion is coming from.
Plus, the goal of the invasion of CO was to control passes through the Rockies.