President Barack Obama shook hands with Cuban President Raul Castro Tuesday at a memorial service for Nelson Mandela, a simple gesture that stoked talk of a possible rapprochement between the leaders of two Cold War foes.

The brief encounter between the U.S. and Cuban president came during a ceremony that celebrated the former South African president’s legacy of reconciliation. Obama was greeting a line of world leaders attending the memorial in Johannesburg before delivering his own eulogy in which he urged a new generation to embrace Mandela’s life work as their own.

More than half a century after the U.S. cut off diplomatic relations with Cuba, such exchanges between American and Cuban leaders are exceedingly rare. U.S. officials often have gone to great lengths to avoid having presidents meet Cuban leaders, even in passing.

Making his way to the podium for his speech, Obama also greeted Brazilian President Dilma Rousseff with a kiss on the cheek. Rousseff and Obama have clashed over reports the National Security Agency monitored her communications, leading the Brazilian leader to shelve a state trip to the U.S. earlier this year in a show of anger.

The U.S. and Cuba have recently taken small steps toward political reconciliation, raising hopes that Washington and Havana could be on the verge of a breakthrough. But skeptics caution the two countries have shown subtle signs of thaw in the past, only to fall back into old recriminations.

In 2009, Obama made waves when he shook hands with the late Venezuelan president Hugo Chavez, a strident critic of the United States, at the Summit of the Americas.

(AP)