The CIA asked Sam Giancana and Johnny Roselli to whack Castro. Giancana and Roselli asked Santo Trafficante to kill him.
According to Jimmy Fratianno it was very easy to kill Castro, in his early days. But Santo decided he wouldn't do it (according to jimmy frattianno).

My question: Why didn't Santo do it? Castro kicked all the mafiosi out of his island (out of the casinos). A big racket was gone..