Key events in U.S.-Cuba relations:
— Jan. 1, 1959: Fidel Castro's rebels take power as dictator Fulgencio Batista flees Cuba. The United States soon recognizes the new government.
— June 1960: Relations begin to sour as Castro veers left. Cuba nationalizes U.S.-owned oil refineries after they refuse to process Soviet oil. Nearly all other U.S. businesses are expropriated by October.
— October 1960: Start of U.S. embargo: Washington bans exports to Cuba, other than food and medicine.
— Jan. 3, 1961: U.S. breaks relations with Cuba and closes embassy.
— April 16, 1961: Castro declares Cuba a socialist state.
— April 17, 1961: U.S.-trained Cuban exiles stage the failed Bay of Pigs invasion aimed at toppling Castro. U.S. intelligence agencies also stage repeated attempts over the years to kill the Cuban leader.
— Feb, 7, 1962: President John F. Kennedy expands embargo, banning almost all Cuban imports.
— October 1962: U.S. blockade forces removal of Soviet nuclear missiles from Cuba. U.S. President John F. Kennedy agrees privately not to invade Cuba.
— April 1980: Mariel boatlift: Cuba says anyone can leave; some 125,000 Cubans flee, causing a refugee crisis for the United States.
— December 1991: Collapse of Soviet Union devastates Cuban economy.
— August 1994: Castro declares he will not stop Cubans trying to leave; some 40,000 take to sea heading for United States.
— Sept. 12, 1998: Five Cuban spies arrested in the United States. They are later convicted. Cuba mounts an international campaign to free them, saying they were defending island against U.S.-based terror attempts.
— July 31, 2006: Fidel Castro announces has had operation, temporarily cedes power to brother Raul. Fidel resigns as president two years.
— Dec. 3, 2009: USAID contractor Alan Gross arrested in Havana, stifling incipient efforts to improve U.S.-Cuba ties under President Barack Obama.
— Dec. 17, 2014: Gross freed and remaining members of Cuban Five spy ring freed as part of prisoner exchange.