Original sentence: CIA documents released in 2005 indicate that the agency had prior knowledge that the bombing was going to take place.Cubana Flight 455 was an Air Cubana flight from Barbados to Cuba that was brought down by a CIA-linked terrorist attack on October 6, 1976
Edited sentence: CIA had concrete advance intelligence, as early as June 1976, on plans by Cuban exile terrorist groups (but not who or when) to bomb a Cubana airliner.Cubana Flight 455 was an Air Cubana flight from Barbados to Cuba that was brought down by a terrorist attack on October 6, 1976.However, Posada stopped being a CIA agent in 1974, but there remained "occasional contact" until June 1976, a few months before the bombing.The FBI's attache in Caracas had multiple contacts with one of the Venezuelans who placed the bomb on the plane, and provided him with a visa to the U.five days before the bombing, despite suspicions that he was engaged in terrorist activities at the direction of Luis Posada Carriles