Forty years ago, the arch-conservative American President Richard M. Nixon shocked his country and the world by visiting communist China, a country that the United States did not recognize and whose soldiers had fought American soldiers in the Korean war.

Last week, that historic occasion was marked in Beijing by Chinese and American officials — and by a former official, Henry Kissinger, who at 88 years of age is the only senior official who was intimately involved in the historic event who is not just alive but still active.

Much has happened since that visit in 1972, which signaled to the world that Washington was making a dramatic change in its China policy and that the diplomatic commitment to the Republic of China government in Taiwan, then still headed by dictator Chiang Kai-shek, was about to end.