All acknowledge that it has not accomplished its core mission of toppling Fidel and Raul Castro.
"All this time has gone by, and yet we keep it in place," said Wayne Smith, who was a young U.S. diplomat in Havana in 1961 when relations were severed and who returned as the chief American diplomat after they were partially reestablished under President Jimmy Carter.
"We talk to the Russians, we talk to the Chinese, we have normal relations even with Vietnam. We trade with all of them," Smith said. "So why not with Cuba?"
In the White House, the first sign of the looming embargo came when President John F. Kennedy told his press secretary to go buy him as many H. Upmann Cuban cigars as he could find. The aide came back with 1,200 stogies.
Kennedy announced the embargo Feb. 3, 1962, citing "the subversive offensive of Sino-Soviet communism with which the government of Cuba is publicly aligned."
It went into effect four days later at the height of the Cold War, a year removed from the failed CIA-backed Bay of Pigs invasion meant to oust communism from Cuba and eight months before Soviet attempts to put nuclear missiles on the island brought the two superpowers to the brink of war.
Washington already had some limited sanctions in place, but Kennedy's decision was the beginning of a comprehensive ban on U.S. trade with the island that has remained more or less intact ever since.
Little was planned to mark Tuesday's anniversary, but Cuban American members of Congress issued a joint statement vowing to keep the heat on Cuba.
Supporters of the policy acknowledge that many U.S. strategic concerns from the 1960s have been consigned to the dustbin of history, such as halting the spread of Soviet influence and keeping Fidel Castro from exporting revolution throughout Latin America.
But they say that other justifications remain, such as the confiscation of U.S. property in Cuba and the need to press for greater political and personal freedoms on the island.
"We have a hemispheric commitment to freedom and democracy and respect for human rights," said Jose Cardenas, a former National Security Council staffer on Cuba under President George W. Bush. "I still think that those are worthy aspirations."
President Obama has said Raul Castro's economic openings are insufficient, and it's unlikely he would do anything in an election year to risk losing support in Florida, which he won in 2008.
Even if he wanted to lift the embargo, the Helms-Burton Act of 1996 stipulates that it would have to be approved by Congress.
