Cuba and Russia were trying to set up Grenada as a SURPRISE, WE COMMIE NOW thing and Reagan saw the opportunity to burnish his anticommie credentials and erase a little bit of the shame from 'Nam. If we hadn't invaded they would have sooner rather than later had red stars popping up out of nowhere like this but with palm trees instead of onion domes
If you really want to look at something interesting, look at the time scales.
Beirut barracks bombing.
82nd and 101st get put on alert, start making plans for a counter strike. 75 starts training up for a counter strike. The plans are all the way down to Battalion and Company level for operational orders.
SUDDENLY
Grab maps of Grenada at the travel agent. No time for NSA or CIA sats!
EVERYONE JUMP ON THE PLANES RIGHT FUCKING NOW!
GO GO GO GO!
One of the initial landings was made by a team of 4-6 (records differ) combat engineers, only 2 with Airborne qualifications, that landed and moved a bunch of bulldozers and shit so the rest could land. (I read his bit in the Army Times) One got a BS-V and a Purple Heart out of it.
Everyone scrambles, but boy are there some interesting targets.
The university, that's an interesting one. They hauled out more than students.
Dust settles, actual mission objectives are slapped with NATIONAL SECURITY with some pretty high up keywords.
It's had rumors for a long time it was more than just "SURPRISE COMMIES!"
That timetable and a couple of the first wave units were pretty fucking suspicious.
But, hey, it was the Cold War. Records are spotty at best and everyone was drunk and stupid.