IT’S ONE thing to know that China runs a far-flung system of detention camps for Muslim Uighurs, a fact of which the world has been aware for the past two years. It’s quite another to see that system in operation. And now we have that kind of visual evidence, in the form of a clandestinely recorded video showing hundreds of Uighur men, handcuffed and gripped by armed guards, being marched through a train station in their native region of Xinjiang. The video has been authenticated by Nathan Ruser, a satellite analyst at the Australian Strategic Policy Institute, a government-supported think tank. Mr. Ruser said it was made in mid-2018 and depicts the transfer of prisoners from one center, in Kashgar, on China’s far western border, to a new facility near Korla, 600 miles deeper into the Chinese interior. Australia’s foreign minister, Marise Payne, called the newly released images “deeply disturbing,” and they certainly are that — as well as a powerful counter to the Beijing government’s claims that it is merely offering Uighurs educational and job-training opportunities to de-radicalize a population prone to terrorism.

Actually, China is engaged in a wide-ranging effort to root out and crush the ancient culture of the Uighurs, who are ethnically Turkic and religiously Muslim. In addition to mass detention, the means employed include arrests, torture and disappearance of political and cultural leaders, as well as technological surveillance of the general population. Xinjiang has always been a “restive” province, loath to submit to domination and colonization by the remote Communist Party authorities in Beijing. But the systematic crackdown occurring now goes well beyond what past isolated acts of anti-government violence might possibly justify.

Indeed, President Xi Jinping seems bent on ending or at least limiting any independent commitment to a belief system other than the one embodied in official Communist Party propaganda. His government’s next target appears to be the 10-million-member Muslim Hui minority, who live not in Xianjiang but in Gansu province, and who have no particular record of separatism or extremism. As The Post’s Gerry Shih reports, government agents have begun purging the Huis’ region of visible symbols of Islam, such as mosque domes and minarets. Arabic script signage has been banned in public spaces, as have sales of the Koran. Some liken what’s happening to the anti-religious frenzies of the Cultural Revolution, but Mr. Xi enforces ideological conformity bureaucratically, not via Red Guard mobs.

China’s systematic anti-Muslim campaign, and accompanying repression of Christians and Tibetan Buddhists, may represent the largest-scale official attack on religious freedom in the world. Other governments must not remain silent. The Trump administration’s condemnations have ebbed and flowed, depending on President Trump’s interest in courting Mr. Xi for trade concessions. Mr. Trump is not alone: Many Western countries’ economic interests dictate their China policies.

There was a welcome moment of U.S. toughness on the sidelines of the U.N. General Assembly on Tuesday, however, when the United States led more than 30 countries, along with nongovernmental organizations, in condemning what a State Department official called the “horrific campaign of repression.” Former Chilean president Michelle Bachelet, the United Nations’ top human rights official, is demanding unrestricted access to China. She should get it but probably won’t, because, when it comes to China’s official cover stories, seeing is disbelieving.

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