The latter script is eerily Orwellian: Should students ask whether their missing parents had committed a crime, they are to be told no, “it is just that their thinking has been infected by unhealthy thoughts. Freedom is only possible when this ‘virus’ in their thinking is eradicated and they are in good health.”

That someone from within the unforgiving, secretive Chinese leadership would take the enormous risk of leaking 403 pages of internal documents to a Western newspaper is in itself amazing, especially since the documents include an 11-page report summarizing the party’s investigation into the activities of Wang Yongzhi, an official who was supposed to manage a district where Uighur militants had staged a violent attack but who eventually developed misgivings about the mass detention facilities he had built. “He refused,” said the report, “to round up everyone who should be rounded up.” After September 2017, Mr. Wang disappeared from public view.

It becomes clear from the documents that Mr. Xi is far more concerned by any challenge to the Communist Party’s image of strength than foreign reaction. Already in May 2014 he told a leadership conference, “Don’t be afraid if hostile forces whine, or if hostile forces malign the image of Xinjiang.” Accordingly, the Chinese government made no effort to deny the leaked documents, but rather portrayed the crackdown in Xinjiang as a major success against terrorism and accused The Times of smearing China’s “antiterrorism and de-extremism capabilities.”

What the documents really reveal is not an effective antiterrorism campaign, but rather the paranoia of totalitarian leaders who demand total fealty in thought and deed and recognize no method of control other than coercion and fear. Mr. Xi and other top government officials reveal in these papers a conviction that the Soviet Union collapsed because of ideological laxity and spineless leadership, and a top security official attributed terrorist attacks in Britain to the British government’s “excessive emphasis on ‘human rights above security.’” And Mr. Xi argued that new technology must be part of the broad campaign of surveillance and intelligence-gathering to root out dissidence in Uighur society, anticipating Beijing’s deployment of facial recognition, genetic testing and big data in Xinjiang.

Whoever leaked these revealing documents obviously disagreed and had the courage to do something about it. His or her brave action is a cry to the world.