Arriving on stage at FNB stadium in Johannesburg to pay tribute to Nelson Mandela, President Barack Obama shook hands with dozens of other world leaders, pausing briefly to grasp the hand of Cuban President Raul Castro.
The greeting quickly sparked a strong debate on Twitter between those who praised and disagreed with the handshake, given that the United States does not share diplomatic relations with Cuba.
"On the streets of Cuba, the gesture was met with surprise and hope for reconciliation," reports CNN’s Athena Jones.
But a senior administration official said it was not "pre-planned encounter."
"Above all else, today is about honoring Nelson Mandela, and that was the President's singular focus at the memorial service," the official continued. "We appreciate that people from all over the world are participating in this ceremony. As the President said, we urge leaders to honor Mandela's struggle for freedom by upholding the basic human rights of their people."
Nonetheless, it was a moment of high symbolism. The U.S. and Cuba have not had diplomatic relations since the Cuban Revolution more than 50 years ago. The President has eased some of the economic embargo and travel restrictions that the administration of President George W. Bush strongly enforced, but relations still are tense. Cuba continues to imprison an American citizen, Alan Gross, who was arrested in 2009 on charges of attempting to destabilize the Cuban government.
Obama knew, of course, that Castro would be on stage. But refusing to shake Castro's hand would not have been in keeping with Mandela's legacy of reconciliation.
"It took a man like Madiba to free not just the prisoner, but the jailer as well to show that you must trust others so that they may trust you; to teach that reconciliation is not a matter of ignoring a cruel past, but a means of confronting it with inclusion and generosity and truth," Obama said in his speech at the memorial service.
It was not the first handshake between American-Cuban leaders. In 2000, at the United Nations, then President Bill Clinton shook hands with Fidel Castro, the leader of the Cuban Revolution, its first revolutionary president, and Raul's brother.
"The question now is whether this hand shake will change history or change nothing," Jones says.