It was early 1972 when the White House announced that President Richard Nixon would fly to Beijing that February for the first ever meeting between a U.S. president and Mao Tse-tung, the Chinese Communist dictator who is estimated to have been responsible for the killing of 20 million or more of his own citizens. Conservatives and others were outraged because Mao was seen, not inaccurately, as just as morally reprehensible as Adolph Hitler and Joseph Stalin.

It was the height of the Cold War between the West and the Communist world in general and the very hot war in Vietnam, where Americans were being killed by the thousands by weapons supplied by the Soviet Union and Communist China. Mr. Nixon had been viewed by friend and foe alike as the quintessential cold warrior and the news that he would meet with Mao came as a shock to just about everyone.

Nixon and Henry Kissinger, his foreign policy guru, justified the trip by arguing that we could no longer ignore an adversary the size of Communist China. They believed an opening to China might indeed head off a future confrontation but were just as convinced that given the cracks in the Communist world at the time, sidling up to Mao would allow them to exploit the emerging problems between China and the Kremlin.

Though the president’s allies may have understood what Nixon and Mr. Kissinger were really up to, most found the very idea that a president of the United States would meet with as ruthless a dictator and enemy as Mao repugnant; this was a man who had the blood of millions on his hands, ran one of the most totalitarian regimes in the world and was a sworn enemy of the United States who had bragged that he had no fear of a nuclear confrontation with America because he believed the survivors who would climb out of the rubble would be Communists.