In the 1960s, China and the United States had no trade relations and no direct diplomatic contacts. At the end of the 20th century, the two nations are major trading partners who regularly swap visits between their heads of state, and the relationship between the world's most populous nation (with its nuclear weapons and rapidly expanding economy) and the world's most powerful nation (standard-bearer of democracy and capitalism) has become increasingly vital to world peace. Though it remains fraught with problems, the relationship between China and America has survived such crises as the Tiananmen massacres and confrontations over Taiwan. James...