The Cuban dictator Batista ran the island as a gambling casino and whore hour for the American upper classes. The U.S. government backed him even though they were aware of his corrupt acts. When the revolution started, some politicians (with a conscience) subtly backed him and prevented U.S. troops or intelligence agencies from undermining the revolution.
There was much celebrating when the dashing young revolutionary won and overthrew the old government. There was a lot of back pedaling when Castro announced that he was a communist and would not be a shill for the U.S.
Cuba has been punished ever since and the people suffered because the U.S. could never come to grips with being out maneuvered.