US President Barack Obama shook hands at Nelson Mandela’s memorial Tuesday with Raul Castro, leader of long-time Cold War foe Cuba, in what Havana called a gesture of hope.

Obama offered the handshake before taking the stage to speak at the ceremony, in a new sign of his willingness to reach out even to the staunchest of US enemies, a US official told AFP.

The United States maintains a five-decade-old embargo against the communist island nation, which Havana says has cost the economy $1.1 trillion.

Seen by millions as they watched the memorial being broadcast live around the world, the surprise handshake was saluted in Havana as a hopeful sign.

Government website Cubadebate.cu ran a photograph of the moment with the caption: “Obama greets Raul: may this image be the beginning of the end of the US aggressions against Cuba.”

It was only the second time in the past 60 years that leaders of the two Cold War antagonists have pressed the flesh.

Cuban leader Fidel Castro and Bill Clinton exchanged greetings in 2000 during the Millennium summit in New York.

Cold War foes Cuba and the United States have had only limited ties for half a century, most of it under the iron fist rule of Raul’s brother Fidel Castro.

The fate of the communist state is a bitter issue in US domestic politics and despite the warm reaction in Havana, it is unclear if Tuesday’s gesture will significantly thaw relations.

Vehemently anti-Castro Cuban-Americans make up a sizable portion of voters and political donors in Florida, a battleground state where US presidential elections can be won or lost.

As a presidential candidate Obama was pilloried as naive and dangerous by rivals from both parties for suggesting that as president he would be willing to talk to foes without preconditions.

In September, the US leader spoke by telephone with Iranian President Hassan Rouhani, in the first such gesture since the 1979 revolution in the Islamic republic.

Obama’s ability to track down and kill Osama bin Laden and a series of drone strikes has largely insulated him from allegations of weakness in foreign and security policy, but the president was careful to pointedly call out oppressive leaders in his speech Tuesday, with Castro just feet away.

“There are too many leaders who claim solidarity with Madiba’s struggle for freedom, but do not tolerate dissent from their own people,” he said, stabbing his finger in the air.

Havana and Washington have not had diplomatic relations since 1961, two years after Fidel Castro came to power in the Cuban revolution.

There was no picture of the Castro-Clinton greeting in 2000, and the White House initially denied it had occurred.

“I couldn’t run out to avoid greeting him,” the elder of the Castro brothers said at the time, adding that the encounter lasted 20 seconds. “It would have been extravagant and rude to do anything else.”

Since Obama took office tensions have eased, with both countries reaching a series of agreements seen as confidence building measures including cooperation on air and maritime rescue, migratory issues.

In 2011 Obama eased restrictions on visas, remittances and travel.

The move was designed to expand religious and educational travel, allow any airport to offer charter flights to the country and restore cultural initiatives suspended by the previous Bush administration.

Talks are under way to resume a direct postal service between the two countries.