U.S. President Barack Obama and Cuban President Raul Castro shook hands on Friday at a summit in Panama.
A photograph showed Mr. Obama and Mr. Castro, both wearing dark suits, chatting in a small group of leaders at the summit's opening ceremony. A White House official confirmed the two men shook hands and spoke briefly.
"This was an informal interaction and there was not a substantive conversation between the two leaders," the official said.
"As we move towards the process of normalisation, we'll have our differences government to government with Cuba on many issues. Just as we differ at times with other nations within the Americas, just as we differ with our closest allies," Mr. Obama said earlier on Friday.
"The days in which our agenda in this hemisphere so often presumed that the United States could meddle with impunity, those days are past," he said.
Colombian President Juan Manuel Santos hailed Obama's push to improve relations with Cuba, saying it was helping to heal a "blister" that was hurting the region.
However, Cuban dissident Guillermo Farinas said civic groups in Cuba have been sidelined from talks and appealed to Mr. Obama to support their push for more democracy.
Mr. Obama, who met with activists from across Latin America, including two Cuban dissidents, appears to be close to removing Cuba from a U.S. list of countries that it says sponsor terrorism.
Its inclusion on the list brings a series of automatic U.S. sanctions and Cuba is insisting it be taken off as a condition of restoring diplomatic ties.
