As a congressional inquiry discovered in 1975, the CIA hatched numerous plots to assassinate Cuban dictator Fidel Castro during Kennedy's presidency, including an attempt to poison his food [source: Kessler]. Did Castro decide to return the favor? Lyndon B. Johnson harbored such suspicions. In a 1967 phone call to acting Attorney General Ramsey Clark that was secretly recorded, LBJ even described a rumor he'd heard about how Castro had captured plotters against him and tortured them into revealing that they were working for the CIA.
"So he [Castro] said, 'Okay. We'll just take care of that,'" LBJ said. "So then he called Oswald and a group in, and told them to ... go set it up and get the job done" [source: Holland].
Oswald was involved with pro-Castro activism and even tried to obtain a visa to visit Cuba in the summer before JFK's death. But clear-cut proof of a Cuban role in the assassination has yet to emerge, and in a 1977 interview, Castro himself said that killing Kennedy would have been "absolute insanity," because the U.S. might have attacked Cuba in retaliation [source: Volkman].