Relations between the United States and Cuba, more strained than neighborly over the past century, have seen US occupations, Cold War enmity, and even the brink of nuclear war.

Here are some key events in US-Cuba relations, as the two sides prepare to restore full diplomatic ties and reopen embassies in their respective capitals:

- 1961: The United States breaks diplomatic ties with Cuba on January 3. On April 17, an invasion force of Cuban exiles organized by the Central Intelligence Agency is routed at the Bay of Pigs.

- 1962: The 1960 US embargo is expanded to cut off all trade with Cuba except food and medicine. Soviet missiles are then discovered in the country, sparking the 13-day nuclear crisis.

- 1965: Cuba allows hundreds of exiles to sail to the United States in the October-November Camarioca boatlift. US President Lyndon Johnson establishes "freedom flights," and 260,561 Cubans leave until the program ends in April 1973.

- 1977: US-Cuban relations improve slightly with the establishment of "Interests Sections" in their respective capitals.

- 1980: As part of the Mariel boatlift, Castro says anyone wanting to leave the country can do so through the port of Mariel. Some 125,000 refugees arrive in Florida by late September.

- 1996: The US Congress passes the Helms-Burton Act strengthening the embargo against Cuba.

- May 2002: Former US president Jimmy Carter visits Cuba, becoming the first US leader in or out of office to do so since Fidel Castro took power in 1959.

- November 2004: Havana bars US dollars for commercial transactions.

- December 2009: Alan Gross, a government contractor for the US Agency for International Development, is arrested for importing banned computer technology for distribution to Cuba's small Jewish community.

- March 2011: Gross is sentenced to 15 years in prison for "acts against the independence or territorial integrity of the Cuban state."

- Spring 2013: US President Barack Obama authorizes exploratory negotiations with Cuba on normalizing ties, leading to secret negotiations, at times aided by the Vatican.

- December 17, 2014: Obama and Castro simultaneously announce plans to normalize ties and the release of prisoners. Cuba releases the 65-year-old Gross and a Cuban spy, while the United States frees three Cubans imprisoned on espionage charges.

- January 12, 2015: US announces that Cuba has released 53 political prisoners as part of the normalization deal. Washington eases travel and trade restrictions a few days later. The embargo, however, remains in place.

- January 21-22: The highest-level US delegation in 35 years holds talks with Cuban counterparts in Havana on migration and the reopening of embassies -- the first round of several held by diplomats.

- January 26: Fidel Castro, Cuba's revolutionary leader, breaks his silence, saying he does not oppose the rapprochement even though he lacks confidence in Washington.

- March 11: A direct telephone link is established between the two countries.

- April 11: Obama and Raul Castro meet in Panama on the sidelines of the Americas summit, the first face-to-face talks between a US and Cuban president since the 1959 revolution.

- May 29: The United States removes Cuba from its list of state sponsors of terrorism, a key stumbling block.

- July 1: Obama and Castro exchange letters confirming the re-establishment of diplomatic ties as of July 20 and the reopening of embassies in Washington and Havana. Obama calls it a "historic step forward."