Students among a crowd of 20,000 celebrate as former Cuban President Fidel Castro delivers a speech in Havana during the 50th anniversary of the Committee for the Defense of the Revolution, the nation's neighborhood vigilance system. (Associated Press)

Students among a crowd of 20,000 celebrate as former Cuban President Fidel Castro delivers a speech in Havana during the 50th anniversary of the Committee for the Defense of the Revolution, the nation's neighborhood vigilance system. (Associated Press)