21 January 2015
Last updated at 10:53
The US and Cuba are due to hold their highest-level talks in decades in the Cuban capital, Havana.
The talks are part of a thaw in relations between the two rivals announced last month in simultaneous speeches by US President Barack Obama and his Cuban counterpart, Raul Castro.
They come only hours after Mr Obama urged Congress to seize the chance to end the US trade embargo against Cuba.
The talks will focus on migration and restoring full diplomatic ties.
The US delegation will be led by Roberta Jacobson, the top US diplomat for Latin America. The last time someone of her level of seniority visited Cuba was 35 years ago.
BBC state department correspondent Barbara Plett Usher says the meetings feel like the beginning of a new era in relations between the two nations.
Our correspondent says the US will be asking for an end to current restrictions on its diplomats so it can upgrade its interest section in Havana to a full embassy.
The Cubans have not made their agenda public, but talks are expected to focus on migration issues on Wednesday and fuller diplomatic relations on Thursday.
On Tuesday, President Obama stressed the importance of the thaw in US-Cuban relations in his State of the Union address to Congress.
He said his decision to engage with Cuba after decades of frozen relations had the potential to “end a legacy of mistrust in our hemisphere”.
He also urged Congress to begin work on ending the US trade embargo against Cuba, which has been in force for more than five decades.
“In Cuba, we are ending a policy that was long past its expiration date. When what you’re doing doesn’t work for 50 years, it’s time to try something new,” he said.
The president said the shift in his administration’s Cuba policy removed “a phony excuse for restrictions in Cuba; stands up for democratic values; and extends the hand of friendship to the Cuban people”.
However, President Obama does not have the power to lift the embargo, only Congress can do that and correspondents say many Republicans are still deeply opposed to this.
Listening to Mr Obama was Alan Gross, the US contractor whose release on 17 December after five years in a Cuban jail was a key part of the deal agreed by Cuba and the US.
Mr Gross was among the guests invited by First Lady Michelle Obama.
In a reflection of the divided views among US politicians on relations with Cuba, Republican House Speaker John Boehner invited Cuban dissident Jorge Luis Garcia Perez.
Mr Garcia Perez, who was held for 17 years in a Cuban prison. has called President Obama’s move a “betrayal” that leaves the island’s opposition “defenceless”.