The US and Cuba have begun historic talks about restoring diplomatic relations
A US embassy in Havana is being planned, among a raft of measures
Cuban leader Raul Castro and US President Barack Obama both made TV addresses
"These 50 years have shown that isolation has not worked," said Mr Obama
The move marks a dramatic shift in a relationship that has been strained since the Cold War era
US citizen Alan Gross was released earlier from a Cuban prison, while the US freed three Cubans jailed for spying
US Republican Senator Marco Rubio has spoken out against easing ties with Cuba. His family fled the country and he's been tipped for a presidential run in 2016.
"Today's announcement initiating a dramatic change in US policy toward Cuba is just the latest in a long line of failed attempts by President Obama to appease rogue regimes at all costs."
Two members of the Cuban Five were earlier released, one in 2011 and another in February. Fernando Gonzalez (below) received a hero's welcome.
Image source, APHe embraced his mother, Magali Llort, before being welcomed by President Raul Castro
Cuba has maintained they posed no threat to the US and were only monitoring anti-communist exiles in Florida with the aim of preventing attacks by exiles on Cuba.
The three Cubans released from the US on Wednesday were members of the Cuban Five, found guilty of conspiracy and failure to register as foreign agents in the US in 2001.
The unnamed US asset was responsible for important intelligence gathering which led to prosecution of multiple individuals. "His return was particularly important to us," the administration official told reporters.
Three Cubans imprisoned in the US have been exchanged for one unnamed intelligence asset held in Cuba for 20 years, a senior US administration official says.
Jeff Flake, a US congressman from Arizona, tweeted, external this picture of Alan Gross on US soil.
Image source, Jeff FlakeAmerican aid worker Alan Gross has arrived at Andrews Air Force Base near Washington from Cuba, according to pictures broadcast on US TV.
He was released by Cuba as part of a deal that also saw the release of three Cubans jailed for spying by the US.
US President Barack Obama and his Cuban counterpart Raul Castro are expected to make simultaneous statements at 17:00 GMT.
American officials have told US media that Washington is looking to open an embassy in Havana in the coming months.
Welcome to our rolling coverage of the historic announcement that the US and Cuba are to begin working towards normalising diplomatic relations.
The announcement marks a huge shift in ties between the two countries, which have been strained for more than 50 years, since the Cold War era.