In Latin America, one revolution often leads to another. So after Guatemala's pro-Communist regime fell, foes of Costa Rica's left-of-center President José Figueres swore that his turn would come next. His redoubtable neighbor, Nicaragua's Dictator Anastasio ("Tacho") Somoza, left little doubt that he would be even happier to see a revolution in Costa Rica than in Guatemala. Tacho is revenge-minded because last April a gang of exiles sneaked into Somozaland from sanctuary in Costa Rica and came perilously close to assassinating him.
Hastily fortified by the promise of emergency U.S. military aid,...