For the millennials in today's reading audience -- this won't make sense unless you are up on your late cold-war history... and the longer post-WWII history of divided Berlin. Mr. Google has lots of helpful advice if you need it.
Imagine a future where Senator Marco Rubio is elected President Marco Rubio in 2016. After being sworn in, he keeps his promise to reverse Obama's thaw with Cuba.
Rubio (in this imaginary presidency) re-imposes the American trade embargo, and once again stops the free flow of people between the two countries.
In the meantime, the technicians at Disney Laboratories finally perfect techniques for bringing back actual U.S. Presidents. Not just robot-presidents... Real Presidents.
With Disney's help President Reagan returns, visits South Florida, and learns that -- 26 years after the end of the cold war -- the U.S. just re-closed its borders with Cuba because "Castro is way too Commie."
The rest of the world has open borders with Cuba, while America erects a big embargo wall.
Reagan checks with Nancy -- asking WWID ("What would I do?) The first lady whispers her answer in his ear, and -- as a result -- a week later they are on a speaker's platform on the bow of a big yacht entering the harbour at Miami -- Rubio's political base.
The yacht cuts engines and drops anchor. Everything goes quiet as Saint Ronnie steps up the the podium, takes the mic, and turns to face Rubio's city.
In a firm, carefully measured voice President Reagan gestures out to sea and says ""Mr. Rubio... Tear. Down. This. Wall."