Anastasia Lin has been denied a visa to enter China to participate in the Miss World pageant. (Jerome Favre/European Pressphoto Agency)

HERE IS a worrying indication of the insecurity of China’s Communist rulers: Not only are they afraid to allow a 25-year-old Miss World contestant into their country, but also they feel the need to slander and belittle her as they bar the door.

Readers may recall the story of Anastasia Lin, about whom we wrote several weeks ago. Ms. Lin was expected in Hainan Island, China, a few days ago to begin representing Canada in the Miss World pageant, but when other contestants began receiving their visas, hers did not arrive. An actor and follower of the spiritual practice of Falun Gong, which is banned in China, Ms. Lin had used the occasion of her crowning last May to speak out for human rights and religious freedom. Her father, who still lives in China, where Ms. Lin was born, immediately came under pressure from local security forces, she wrote in a Post op-ed in June. She wondered if China was stalling on the visa because of her political views. We wondered if the Miss World pageant would have the self-respect to relocate its pageant if some contestants were excluded.

Now we have some answers. Having received no reply from Chinese authorities, and facing a deadline to compete, Ms. Lin bought an airline ticket via Hong Kong to Hainan. In Hong Kong this weekend, authorities prevented her from boarding her connecting flight to the mainland, and officials at the Chinese Embassy in Canada acknowledged that she is “persona non grata.”

The regime-sanctioned newspaper Global Times fretted about the public relations fallout: “When such a 25-year[-old] pretty girl grumbles that she is denied a visa for speaking the truth and criticizing the Chinese government,” the newspaper wrote, “her words can easily gain sympathy from the Western public that already holds prejudices against China.” But, the Global Times article said, people should not be fooled: “Lin has to pay a cost for being tangled with hostile forces against China.”

In a telephone conversation from Hong Kong, Ms. Lin speculated that the regime “wants to use me as an example to other overseas Chinese who want to speak up, including journalists and scholars.” We agree that is likely part of the story. China has succeeded, almost unseen, in squelching debate beyond its borders simply by threatening to deny visas to people, such as China scholars, who depend on access for their livelihood. (Miss World is not moving its pageant.)

But we also think the regime feels genuinely threatened by anyone who doesn’t toe its line. President Xi Jinping and his Politburo say they want market-oriented reform, but simultaneously they are tightening the screws on civil society, Internet debate, the media, independent churches or anything else that might challenge the Communist Party. In the short run, that hurts people such as Ms. Lin and internal critics who more and more are winding up in prison. In the long run, it can only hurt China itself, as the regime becomes more and more brittle, isolated and afraid.