''I want to thank you for the Bay of Pigs,'' Che Guevara told me in Uruguay during an unexpected meeting at a party for a Latin American diplomat in 1961. ''It solidified our rule and discouraged our middle-class enemies.''

''You're welcome,'' I replied. ''Now, maybe you'll invade Guantanamo.''

''Never,'' he laughed.

At the height of the cold war, and with strong Communist movements in other Latin American countries, the unanticipated transformation of Cuba into a Communist outpost seemed a potential threat to our security. The policy of containment had broken down only 90 miles from Florida.

Yet little more than a year later, the withdrawal of Soviet missiles from Cuba changed the atmosphere, and Kennedy dispatched an emissary to talk with the Cuban delegate to the United Nations, in hopes of laying the groundwork for some rapprochement.

Then the president died, and the embargo was frozen in place for four more decades, long after the reasons for it had evaporated. In this time, Soviet Communism weakened and tumbled. The Communist-led movements in Latin America disappeared. We welcomed trade with the Soviet Union and China. Yet through it all the embargo on Cuba stayed in place, the historical artifact of a cold war that had ended.

This anomalous policy owed its durability to Florida politics. A large and passionate exile community in Miami turned against any party and any politician who seemed willing to dilute our hostility toward the Cuban government.