Assessing the visit so far, Foreign Policy magazine describes, external Mr Obama's progress in normalising relations relations as "significant".

But it warns that the president will not be able to fully lift financial penalties against Havana - one of President Castro's main demands - while Republicans control the US Congress.

Image source, Reuters

Welcome to our live coverage of President Barack Obama's historic three-day visit to Cuba. We're resuming our updates as Mr Obama prepares to address Cubans at El Gran Teatro de La Havana on the final day of his trip. The US president is also due to meet civil society activists, and will attend a baseball game between the Tampa Bay Rays and the Cuban national team.

Social media can be relied upon to highlight the strangest moments during formal news events. Twitter users have been sharing this awkward exchange at the end of the news conference, when President Castro apparently picked up President Obama's arm and waved it around.

Tara McKelvey
BBC News, Havana

Karla Olivares, an independent journalist from Cuba, says she was surprised by the way President Castro acted during the news conference.

"He talked more than usual" she tells me. She says she was most struck by what he said about political prisoners - that Cuba didn't have any.

When asked how she feels about his claim, she smiles and says: "It's complicated."

For decades, Cuba has had one of the worst press freedom records in the world. BBC Monitoring has taken a look at some of the ways Cubans manage to get around the censors. Read more here.

Mr Obama says it is not just Cuba that the US has "deep disagreements" about human rights with - it also has disagreements with China and Vietnam. 

Defending his decision to go to Cuba, he says:  "I believe if I engage frankly, clearly, stating our beliefs but I can't force change on any country -  it ultimately has to come from within - that is a more useful strategy,"  he says. "I have faith in people".

President Obama says family and cultural ties between the US and Cuba, which are only 90 miles (150km) apart, are so strong that everyone would benefit from the ties being strengthened. "There is enormous hope that there can be reconciliation," he said.

A bit more about the message President Obama left in the guest book he signed after he laid a wreath at the memorial dedicated to the memory of Jose Marti. 

"It is a great honor to pay tribute to Jose Marti, who gave his life for independence of his homeland. His passion for liberty, freedom, and self-determination lives on in the Cuban people today,'' he wrote.

The Cuban president says more of the news conference questions should be directed to his US counterpart.

Earlier Mr Castro was asked whether he supported Donald Trump or Hillary Clinton to become Mr Obama's successor, but he said simply that he could not vote in November's election.

President Obama welcomed President Castro's comments on areas "where he believes we are falling short". Earlier Mr Castro highlighted access to education and healthcare among his concerns.

"We should not be immune to criticism," said Mr Obama.

Mr Castro is responding to a question about political prisoners - sort of.

"What political prisoners?" he says. "Can you give me some names, or a list afterwards?"

President Obama thanked President Castro for his "spirit of openness" but said the relationship between the two governments would "not be transformed overnight". 

"The US and Cuba are now engaged in more areas than in any other time in my lifetime," he said.

"If we stay on this course we can bring a brighter future for both the Cuban and American people."

Mr Obama has hailed a "new day" in US-Cuba relations and said he brings greetings and friendship of the American people to Cuba. 

He has made it clear the US will continue to speak up on behalf of democracy, the freedom of expression and human rights, he said.