Could first presidential handshake in 13 years signal a US-Cuba thaw?

President Barack Obama and his Cuban counterpart, Raul Castro, shook hands on Tuesday in a gesture so unprecedented that many observers were tempted to see it as a sign that Nelson Mandela’s memorial had provided the setting for a slight thaw between the leaders of the long-hostile countries.

Obama and Castro were among the speakers eulogizing the South African liberation icon in a rally at the Soccer City stadium in Johannesburg — a reminder that Mandela had accomplished the rare feat of befriending both Cuba and the United States. Obama extended his hand to the Cuban leader as he passed along a line of foreign dignitaries en route to the dais.

Though Obama lingered for just a few seconds before shuffling on to greet Brazil's President Dilma Rousseff, it was enough time for his body language to suggest a willingness to reach out to the leader of a country that has been at loggerheads with the U.S. since the 1959 revolution brought Castro's older brother, Fidel, to power. With Cuba under heavy U.S. sanctions, and diplomatic relations all but severed since the '60s, the last time U.S. and Cuban presidents greeted each other so cordially was in 2000, when then-Presidents Bill Clinton and Fidel Castro shook hands at the U.N. General Assembly.

The memorial service afforded a rare opportunity for interaction between the two leaders because, although the U.S. operates a limited diplomatic mission in Havana, relations were otherwise severed amid the anti-communist fervor of the Cold War.

The break was coupled with an airtight embargo imposed on Cuba beginning in 1962, which is viewed by many Americans and almost all U.S. allies as a relic of the Cold War that has proved ineffective in promoting political change in Havana. It has long been conventional wisdom that the embargo is kept in place by domestic political considerations — particularly in the swing state of Florida, where anti-Castro Cuban influence is strongest.

Obama is not running for re-election, of course, but even if he wanted to lift the embargo, the decision is not in his hands. When President Bill Clinton, with one eye on his own re-election prospects, signed into law the Helms-Burton Act of 1996, he transformed the embargo from an executive order into an act of Congress — which can be undone only by the legislature. And Congress is unlikely to reverse the embargo absent fundamental political change in Cuba.

“The embargo is a thorny issue for the U.S.,” Duany said. “For that to be lifted there’s a long list of things that first need to be addressed, including increasing freedoms” for Cuban citizens.

Public opinion polling indicates that more than half of Americans oppose the embargo, and the U.S. Chamber of Commerce estimates it costs the United States $1.2 billion per year in lost exports. But the authoritarian Cuban government’s poor human rights record and severe restrictions on its people’s liberties have grounded any high-level negotiations.

“The government of Raul Castro continues to enforce political conformity using short-term detentions, beatings, public acts of repudiation, travel restrictions and forced exile,” says Human Rights Watch.

Of particular concern to the U.S. is the 2009 arrest and subsequent conviction of American government subcontractor Alan Gross, who Cuba alleges was working as a spy for the U.S. government. Cuba sentenced Gross to 15 years in prison for distributing satellite phones and computers to members of Cuba’s Jewish community.

In his eulogy of Mandela on Tuesday, Obama issued a stern rebuke of such human rights abuses, which many analysts suspect was directed at the man who had moments ago shaken his hand. “There are too many leaders who claim solidarity with Madiba's struggle for freedom,” he said, using Mandela's clan name, “but do not tolerate dissent from their own people.”

Even as analysts are divided on the weight and intention behind Tuesday’s handshake, they agree that certain pieces might be falling into place for improved U.S.-Cuba relations.

The ascension of Raul Castro to the presidency in 2008, due to the deteriorating health of his brother, Fidel, has been viewed by some as harboring the potential for economic reform — Cuba remains hidebound by a Soviet-era planned economy, which has had to make do for the past two decades without the massive subsidies from Moscow on which it was constructed. Despite slow progress and the setback of the Gross case, the new president of Cuba has made overtures to the U.S. and even engaged in negotiations to restore mail service between the countries.

“I think he’s more pragmatic than his brother, Fidel,” said Duany, noting that Raul Castro has lifted some travel restrictions, allowing many Cubans to leave the country for the first time, and allowed for private industry to take a faint foothold in the communist nation.

While hard-line Cuban-Americans remain vocally opposed to any thaw in U.S.-Cuba ties, opinion on the embargo has become more divided in that community over the years. It remains to be seen whether Obama is willing to antagonize legislators committed to the harder line at a moment when his domestic agenda faces political peril.

Still, while only Congress can lift the sanctions, analysts say warming relations between Obama and Castro could lead to the gradual erosion of the embargo — if the two are genuinely committed.

“At the end of the day,” said Hanson, “to totally normalize relations Congress would have to get involved, but there are an awful lot of things the executive branch can do to move things forward.” Removing Cuba from the State Department’s list of state sponsors of terror — which, coincidentally, included Mandela’s South Africa until 2008 — would be a start.

Doing so might in turn prompt a quid pro quo from Cuba — perhaps the release of Alan Gross.

And once significant concessions are made, Hanson added, “the logic of the Helms-Burton Act begins to fade away."