U.S. government organizations , including the FBI , had been monitoring Cuban spy activities for over 30 years , but made only occasional arrests . However , after the two Brothers to the Rescue aircraft were shot down by Cuban MiGs in February 1996 and four U.S. citizens were killed , on the basis of information sent to Cuba by an infiltrator of the group , the Clinton administration launched a crackdown . According to U.S. attorney José Pertierra , who acts for the Venezuelan government in its attempts to extradite Luis Posada Carriles , the crackdown was aided by the cooperation of the Cuban authorities with the FBI in 1997 . The Cubans provided 175 pages of documents to FBI agents investigating Posada Carriles 's role in the 1997 bombings in Havana , but the FBI failed to use the evidence to follow up on Posada . Instead , they used it to uncover the spy network that included the Cuban Five . According to FBI evidence at the trial , the FBI had been monitoring the communications of Hernández , whose information enabled the shootdown , for several years prior to that event . He was not arrested until 1998
1997 bombings in Havana
1997 Cuba hotel bombings
Cuban Five