Leaked documents purportedly drawn up by China’s ruling Communist Party (CCP) appear to reveal the internal mechanisms governing a vast network of internment camps used to extrajudicially detain at least a million Muslims in the nation’s far western province of Xinjiang.

Camps must adhere to a strict regiment of total physical and mental control, a gruelling diet of political indoctrination, vice-like security protocols, strict secrecy and “labor skills training” for longer-serving inmates, according to the China Cables, a cache of classified government papers published by the Washington-based International Consortium of Investigative Journalists (ICIJ) on Sunday.

The Chinese government has called the documents “pure fabrication and fake news.” Despite initially denying the existence of the camps altogether, Beijing officials have since changed tack, claiming that they are for “education transformation” and “vocational training” in the fight against the “three evils” of “separatism, terrorism and extremism,” which form part of its regional Strike Hard Campaign Against Terrorism.

Yet the contents of the documents — some of which are signed in the name of Zhu Hailun, the top security official and deputy Communist party chief in Xinjiang — closely mirrors testimony TIME has independently received from over a dozen interviews with former camp inmates and family members of detainees.

Orynbek Koksebek, 39, was arrested in November 2017 after authorities accused him of being a traitor for seeking duel citizenship in neighboring Kazakhstan. He says he was forced to learn the Chinese language and fed endless propaganda about the glory of the CCP under strongman President Xi Jinping. During one interrogation, he says he was thrown into a hole in the ground, doused with cold water and severely beaten. Orynbek’s torture was so unrelenting that he says he eventually attempted suicide. Other inmates have reported rape, torture with electric batons, and other systematic abuses.

“Whenever we saw a bird or a dog outside, we felt jealous of their freedom,” he tells TIME in Almaty, Kazakhstan, where he has escaped to. “Our fate felt endless.”

Predominantly Muslim ethnic minority groups — mainly the Turkic Uighurs, but also Kazakhs, Uzbeks and Kyrgyz — comprise over half of Xinjiang’s 25 million people. An influx of moneyed ethnic Han settlers into the resource-rich region — China’s largest — has helped raise living standards, says the Beijing government, but conversely spurred accusations that local culture has been eroded. Uighurs agitating for greater autonomy have launched a spate of terrorist attacks in recent years.

Other than governing inmates’ treatment inside the camps, the China Cables also detail how the vast troves of personal data amassed through facial recognition cameras, manual searches, and other surveillance apparatus can be used to identify candidates for detention. This chimes with reverse engineering performed the advocacy group Human Rights Watch on the Integrated Joint Operations Platform security app used by police in Xinjiang.

“I’ve seen numerous police reports that indicate a person was detained because they were part of a Quran Study Group,” says Darren Byler, a postdoctoral researcher specializing in the Xinjiang crisis at the Center for Asian Studies at the University of Colorado, Boulder.

The China Cables also contain explicit directives to detain Uighurs with foreign citizenship and repatriate ethnic Muslim Chinese citizens living abroad using China’s embassies and consulates in the dragnet. Again, this is corroborated by witness testimony of exiled Uighurs experiencing threats and intimidation from Chinese officials overseas in breach of local laws and diplomatic protocols.

The Xinjiang camp network has been described as a “horrific campaign of repression” by the U.S. and condemned by 22 nations at the U.N. However, a total of 37 nations, including many with Muslim majorities, have defended China’s record, indicative of the economic and political clout of the world’s number two economy at a time when rival superpower the U.S. is withdrawing from international commitments under Donald Trump.

“Everybody’s afraid that if they take a stand, they’re going to be the only one and then they’re going to get hit,” says Gene Bunin, a researcher into Uighur language and culture based in Central Asia. “Because they don’t expect others to do the same.”

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Write to Charlie Campbell at charlie.campbell@time.com.