US Secretary of State John Kerry has hailed a "new beginning" after a ceremony marked the reopening of the Cuban embassy in Washington.
The symbolic event saw the raising of the Cuban flag in the US capital for the first time in 54 years - the latest milestone as the two former Cold War foes continue to rebuild diplomatic ties.
Cuba and the US officially re-established embassies in Washington and Havana respectively at 12.01am on Monday, with the Cuban flag hung in the lobby of the State Department.
The American flag will be raised over the US embassy in Havana during a ceremony attended by Mr Kerry in August.
In another step forward, the Secretary of State hosted Cuban Foreign Minister Bruno Rodriguez - the country's first such official to visit Washington for talks since the 1959 Cuban Revolution.
At the ceremony, Mr Kerry said: "Today, with the opening of our embassies and the visit of the foreign minister, we are taking an historic and long overdue step in the right direction."
He added that the process of normalising relations between the two countries will be "long and complex", and urged "patience".
One issue which remains unresolved is the US military base in Guantanamo Bay, Cuba, which Mr Rodriguez highlighted in prepared remarks at the ceremony.
He said: "The historic events we are living today will only make sense with the removal of the economic, commercial and financial blockade, which causes so much deprivation and damage to our people, the return of occupied territory in Guantanamo, and respect for the sovereignty of Cuba."
Mr Kerry said the US had no intention of altering its existing lease arrangement regarding the naval base at this time.
The US economic embargo against Cuba also remains in place and can only be lifted by Congress.
Republican presidential candidates have vowed not to repeal the embargo, and have threatened to roll back President Barack Obama's promotion of closer ties between the two countries.
Relations between the US and Cuba began to deteriorate after the 1959 Cuban Revolution overthrew the Batista government.
After the communist government began nationalising US industries, America responded by banning exports to the island and halting the supply of oil.
The move pushed Cuba towards consolidating its trade relations with the former Soviet Union, which culminated in the failed Bay of Pigs invasion in 1961 and the discovery of Soviet missile sites in Cuba - sparking the Cuban Missile Crisis in 1962.
In December last year, Mr Obama and Cuban President Raul Castro made the breakthrough announcement that the two governments would begin working on normalising relations.
In May, the US removed Cuba from its list of state sponsors of terrorism and both countries agreed to re-establish full relations on 1 July.