Fidel Castro (left) and his brother, Raul, have been the only two rulers Cuba has known since 1959. Raul, the current Cuban president, said Sunday that he will relinquish power by the end of his recently begun five-year term. The U.S. State Department met the news with a lukewarm reaction. (Associated Press)

Fidel Castro (left) and his brother, Raul, have been the only two rulers Cuba has known since 1959. Raul, the current Cuban president, said Sunday that he will relinquish power by the end of his recently begun five-year term. The U.S. State Department met the news with a lukewarm reaction. (Associated Press)