HAVANA (REUTERS) - For sure it's just what Mr Nelson Mandela would have wanted, but does it amount to more than that? The historic handshake between US President Barack Obama and Cuba's Raul Castro at a memorial for Mr Mandela on Tuesday in Johannesburg was greeted on the streets of Cuba with surprise and hopes of improved relations.

Reaction was more muted in Miami, where Cuban exiles have had a hard time accepting Mr Mandela's respect for Cuban leader Fidel Castro.

Mr Castro's smile as Mr Obama moved to shake his hand on the way to speak at the ceremony was seen by many Cubans as a signal of reconciliation, after more than a half-century of bitter ideological and political differences between the two countries whose shores are separated by only 90 miles (145 km).

"I never imagined such a thing could happen," Ms Yesniel Soto, a 25-year-old government worker, said on her way to work in Havana. "I see it as something that has begun to change, a change we are all hoping for."

The two presidents' civil behavior towards one another was the latest sign of a change in tone in the usually hostile rhetoric between the two governments.

Officials on both sides have spoken of a new gravity and pragmatism in their dealings with one another. And last month in Miami, Mr Obama recognized for the first time Mr Castro's efforts to reform the Soviet-style economy, adding that US policy, which includes a long-standing trade embargo on Cuba, was outdated.

The handshake was not planned and the two did no more than exchange greetings, a White House aide said.

"Perhaps the American and Cuban presidents grasp, with this handshake, that the work they have to do together is far easier than South Africa's struggle against apartheid," said Ms Julia Sweig, director for Latin America Studies at the Council on Foreign Relations in New York.

"It can't hurt, but it's not significant," said Mr Philip Peters, founder of the Cuba Research Center and author of The Cuban Triangle blog.

"What matters is whether President Obama will conduct relations as he does with all other countries that have different political systems. That requires a decision, not a handshake," Mr Peters added.

Cuban state-run television broadcast Tuesday's pressing of the flesh without commentary, simply as part of the footage of Castro's speech at the tribute in South Africa.

There has been no official comment on the encounter, but official blogger Yohandry Fontana played up the historic event, tweeting a photo of the handshake.

Some Cuban exiles downplayed the greeting, the first between sitting presidents of the two countries since 2000.

"The handshake was unfortunate, but unavoidable and inconsequential," said Mr Mauricio Claver-Clarone, director of Cuba Democracy Advocates in Washington, which promotes human rights.

"Much more important were Mr Obama's words, which I believe were directed at Mr Castro," he added, referring to the US president's speech at the event.

"There are too many leaders who claim solidarity with Madiba's struggle for freedom, but do not tolerate dissent from their own people," Mr Obama said, using Mr Mandela's clan name.

US Representative Ileana Ros-Lehtinen, a Republican, laid into Secretary of State John Kerry during a committee hearing in Washington on Tuesday, saying "Mr. Secretary, sometimes a handshake is just a handshake, but when the leader of the free world shakes the bloody hand of a ruthless dictator like Raul Castro, it becomes a propaganda coup for the tyrant."

In a statement, the Cuban-born Ros-Lehtinen called the handshake "nauseating and disheartening," noting that Cuban security officials detained several dissidents on Tuesday during street protests to mark International Human Rights Day.

SNUBBED

Mr Mandela was famously snubbed by Cuban exiles in Miami in 1990, when he visited the city after making comments in support of Mr Fidel Castro.

Miami's Cuban-American mayor Xavier Suarez declined to honor Mr Mandela with a proclamation or the keys to the city, prompting a three-year boycott of Miami led by African-American business and community leaders.

During Mr Mandela's 27 years in prison, Mr Castro was a leading voice against apartheid when some other world leaders were reluctant to speak out.

A letter signed by five Miami area mayors said Mr Mandela's support for the Cuban leader, as well as former Palestine Liberation Organization leader Yasser Arafat and the late Libyan dictator Muammar Gaddafi, was "beyond reasonable comprehension."

The only previous known handshake between US and Cuban presidents since the 1959 revolution was in 2000 at the United Nations, when, in a chance encounter, Mr Fidel Castro shook the hand of President Bill Clinton. That handshake, however, was not recorded for posterity as it took place out of sight of cameras.

Mr Richard Nixon, as US vice president, was photographed with Mr Fidel Castro shortly after the Cuban Revolution in 1959. Mr Jimmy Carter also met both Mr Fidel and Mr Raul Castro after his presidency ended.

In the context of Mr Mandela as a peacemaker, Cuba's Catholic Church took note of the significance of the Obama-Castro handshake.

"One hopes that the example of Mandela continues being an inspiration to move further than a formal gesture like this, since Barack Obama and Raul Castro have said a number of times in their own ways that now is the time to change the style of the relations between Cuba and the United States," church spokesman Orlando Marquez told Reuters.