President Obama shared a brief handshake with Cuban President Raul Castro at the Nelson Mandela memorial service on Tuesday, in a moment fraught with symbolism and history.

The exchange came as the president made his way to the podium to deliver remarks about Mandela's legacy, and the White House insisted the handshake was intended in the spirit of the day.

"This wasn't a pre-planned encounter," said an administration official. "Above all else, today is about honoring Nelson Mandela, and that was the president's singular focus at the memorial service. We appreciate that people from all over the world are participating in this ceremony."


The administration official also noted that in his remarks, Obama urged world leaders to honor Mandela's struggle for freedom by upholding basic human rights within their own country.

"There are too many leaders who claim solidarity with Madiba's struggle for freedom, but do not tolerate dissent from their own people," Obama said. "And there are too many of us on the sidelines, comfortable in complacency or cynicism when our voices must be heard."

The incident is believed to be the first contact between the president and Castro. The United States and Cuba have not had formal diplomatic relations for more than 50 years, and the U.S. maintains an economic embargo against its Cold War foe.

It was not, however, the first handshake between and American and post-revolutionary Cuban president. In 2000, President Clinton shook hands with Fidel Castro at a meeting of the United Nations. That was the first handshake between Castro and an American president since 1959, when Richard Nixon met with the Cuban leader shortly after he took power.

The White House has moved in recent years to ease the economic restrictions toward Cuba.

At a fundraiser in Miami last month, Obama told donors the U.S. needed to be "creative" and "thoughtful" as it continued to update its policies toward Cuba.

"Keep in mind that when [Fidel] Castro came to power, I was just born," Obama said. "So the notion that the same policies that we put in place in 1961 would somehow still be as effective as they are today in the age of the Internet and Google and world travel doesn't make sense."

The president has loosened restrictions on travel to the communist nation, allowing Cuban-Americans to make unlimited trips and send unlimited amounts of money to family members.

In 2011, the White House said it would allow students seeking academic credit and churches making religious trips to visit the island.

Additionally, the administration expanded the number of U.S. airports permitted to offer charter service to the island and allowed so-called "purposeful travel" via a licensing process intended to weed out pleasure trips.

It was on one of those permits that performers and Obama donors Jay Z and Beyonce traveled to Cuba for on their fifth wedding anniversary earlier this year.

The White House drew criticism over a Jay Z song that bragged about the trip and included the lyrics "boy from the hood but got White House clearance." The lyrics also say Obama told him "chill, you gonna get me impeached."

The White House denied a role in helping the performers obtain permits.

Secretary of State John Kerry has long been critical of the 50-year old embargo of the island nation. in 2009, he proposed a bill to remove the travel ban entirely, saying the policy "actually furnished the Castro regime with an all-purpose excuse to draw attention away from its many shortcomings."