The orders surprised the Cuban intelligence officer. Most days in his tiny communications hut, just outside Fidel Castro’s isolated family compound on the west side of Havana, were spent huddled over his radio gear, trolling the island’s airwaves for the rapid-fire bursts of signals that were the trademark of CIA spies and saboteurs, pinpointing their location for security forces.

But now his assignment had abruptly been changed, at least for the day. “The leadership wants you to stop your CIA work, all your CIA work,” his boss said. Instead, the officer was told he had a new target: Texas, “any little detail small detail from Texas.” And about three hours later, shortly after mid-day on Nov. 22, 1963, the shocked intelligence officer had something to report that was much more than a small detail: the assassination in Dallas of President John F. Kennedy.

“Castro knew,” the intelligence officer would tell a CIA debriefer years later, after defecting to the United States. “They knew Kennedy would be killed.”

The defector’s tale is reported in a book to be published next month by retired CIA analyst Brian Latell, the agency’s former national intelligence officer for Latin America and now a senior research associate at the University of Miami’s Institute for Cuban and Cuban American Studies.

The book, Castro’s Secrets: The CIA and Cuba’s Intelligence Machine, is the first substantial study of Fidel Castro’s intelligence operations. Based on interviews with Cuban spies who defected as well as declassified documents from the CIA, the FBI, the Pentagon and other national security organs, it contains a good deal of material likely to stir controversy, including accounts of how Castro’s spies have carried out political murders, penetrated the U.S. government and generally outwitted their American counterparts.

But nothing is more potentially explosive than Latell’s claim that Kennedy’s assassin, Lee Harvey Oswald, warned Cuban intelligence officers in advance of his plans to kill the president. Latell writes that Oswald, a belligerent Castro supporter, grew frustrated when officials at the Cuban embassy in Mexico City refused to give him a visa to travel to the island, and promised to shoot Kennedy to prove his revolutionary credentials.

“Fidel knew of Oswald’s intentions — and did nothing to deter the act,” the book declares.

Even so, Latell maintains his work is sober and even reserved. “Everything I write is backed up by documents and on-the-record sources,” he told The Miami Herald. “There’s virtually no speculation. I don’t say Fidel Castro ordered the assassination, I don’t say Oswald was under his control. He might have been, but I don’t argue that, because I was unable to find any evidence for that.

“But did Fidel want Kennedy dead? Yes. He feared Kennedy. And he knew Kennedy was gunning for him. In Fidel’s mind, he was probably acting in self-defense.”

If Latell’s prose is sober, the events it describes are anything but. Castro’s Secrets, to be published by Palgrave Macmillan, explores a confusing and deadly chapter of the 1960s when the Cold War nearly turned hot. The United States, fearful that Castro’s revolution would provide the Soviet Union a toehold in the Western Hemisphere, backed a bloody invasion of anti-communist Cuban exiles at the Bay of Pigs. The Soviets put nuclear missiles in Cuba, which left the entire world teetering on the brink of war for two weeks.