Funny, but the answer is that part of the Kennedy-Khrushchev agreement to end the Cuban Missile Crisis was that the United States wouldn't invade Cuba, and anyone else with the force to do so was a NATO member/American ally.
This is speculation, but looking at how the Cold War played out, then without that agreement the U.S. likely would've invaded Cuba at some point or other. It was still a good agreement overall because of the Moscow-Washington Hotline getting installed, though one can look at history and wonder if the Cuban people would've been better off living in an American territory similar to Puerto Rico instead of a backwards impoverished dictatorship. Hotline Agreement was good though -