Americans should take heed: Censorship that starts in China doesn’t stay in China. The power of the Chinese state distorts U.S. discussion of China, from Facebook’s ban on discussion of the possibility that Covid-19 originated in a Wuhan lab—lifted only in late May—to the harassment and demonetizing of YouTube personalities who criticize Mr. Xi. Similar pressures silence the U.S. movie industry. Hollywood hasn’t had a major production critical of China since 1998, when Disney CEO Michael Eisner asked forgiveness for depicting China’s brutalization of Tibet in “Kundun.” Chinese youth receive years of official indoctrination about their country’s “century of humiliation” by foreign powers beginning in the 19th century. But knowledge of the far greater damage Mao inflicted on his own subjects in the 20th century is buried. This version of history is also silent about the sacrifices made by the “American imperialists” who defeated Imperial Japan and liberated China in World War II. That assault on historical truth also reinforces dangerous feelings of grievance in a generation of young Chinese. One day their belligerence could lead China to war. Already, the nationalist enthusiasm for boycotts of companies that protest China’s mistreatment of its Muslim minorities is a bad sign for China’s peaceful relations with the rest of the world.