President Obama And Cuba's Raul Castro Shake Hands

It happened during the memorial service for Nelson Mandela on Tuesday.

President Obama had a quick chat and shook hands with Cuban President Raul Castro at the memorial service for former South African President Nelson Mandela.

It appeared to be a friendly exchange.

The United States has not had diplomatic relations with Cuba since the communist revolution led by Castro's brother Fidel more than 50 years ago.