Not really a travel question - more of a political question.
As I understand it Cuba and America have nothing to do with each. American citizens can't travel to Cuba and American money and credit cards aren't accepted.
Why then does the USA have a detention centre in Cuba? How does that work??
The lease onGuantanamo dates from 1903 before the revolution and has a clause that it can only be recinded with the agreement of both parties - something the US is not about to agree to.
Apparently Castro has a drawer full of US cheques for the lease payments. He has never cashed any of them.