Operation 40 was the code name for a top-secret Central Intelligence Agency-sponsored counterintelligence and counterinsurgency group composed of CIA officers and anti-Castro Cuban exiles.

King argued that after the recent Cuban Revolution, there now existed a "far-left" dictatorship "which, if permitted to stand, will encourage similar actions against U.S. holdings in other Latin American countries.

[5] Dulles forwarded King's memo to the National Security Council, which approved the formation of a working group to devise "alternative solutions to the Cuban problem.

[3][7] At a White House meeting on 17 March 1960, a plan entitled "A Program of Covert Action Against the Castro Regime" was presented to President Dwight Eisenhower.

[9] The plan called for a broad range of intelligence, political, paramilitary, and psychological warfare operations to topple Cuba's communist government.

Operation 40 consisted of Cuban exiles—many of whom had served in the Bureau for the Repression of Communist Activities under Fulgencio Batista—joined by a small number of American CIA agents.

The act was a CIA operation carried out by various saboteurs who boarded the ship in its port of origin and placed explosives which were detonated by a device which responded to the change in pressure when the cargo was being unloaded.

"[16] While these sabotage operations were occurring in 1960, another CIA-sponsored group of Cuban exiles known as Brigade 2506 was being equipped and trained in Guatemala for an upcoming invasion of Cuba.

[17][18] Prior to the invasion, Operation 40 reportedly purged Brigade 2506 (under the orders of Manuel Artime and E. Howard Hunt) of any liberal, left, or otherwise anti-Batista members.

However, José Raúl Varona González, the intelligence officer in Brigade 2506, was captured, interrogated, and revealed Operation 40's existence to Cuban officials.