CHINA COULD hardly make it more clear that two Canadian citizens it has imprisoned in harsh conditions are political hostages. Michael Kovrig, a former diplomat who works for the International Crisis Group, and Michael Spavor, a businessman who promotes exchanges with North Korea, were arrested last December, just days after Canada detained Meng Wanzhou, a top executive of the Chinese tech firm Huawei, on a U.S. warrant. No evidence of wrongdoing was made public, though some reports said the two men were accused of failing to register under a restrictive new law on nongovernmental organizations.

Last Friday, the Canadian Justice Department authorized an extradition hearing for Ms. Meng, who has been indicted on U.S. bank fraud charges; on Monday, an official Chinese website duly escalated the charges against Mr. Kovrig and Mr. Spavor, saying they had collaborated in stealing state secrets, a charge often used in political cases. Beijing’s message is crude: Unless and until Ms. Meng is freed, it will continue to persecute these Canadians.

The contrast between the cases is stark. Ms. Meng, who is Huawei’s chief financial officer and the daughter of its founder, is charged with bank fraud. She is alleged to have lied to banks about Huawei’s ownership stake in a Hong Kong company that sold U.S. technology to Iran in violation of sanctions. Released on bail, she has been living in one of the two large mansions she owns in Vancouver while awaiting her extradition hearing.

In contrast, Mr. Kovrig is isolated in a Beijing prison where he is denied access to lawyers and his family. The New York Times reported that he had been interrogated continuously and was not allowed to turn the light off in his cell at night. Mr. Spavor is believed to be held in similar conditions in the city of Dandong. The new Chinese claim is that Mr. Spavor was helping Mr. Kovrig gather secret information. In fact, the former is an expert on North Korea and the latter was researching a report on that country for the International Crisis Group. Both have worked openly in China for years; the notion that they were spies is ludicrous.

Canada’s government has, to its credit, refused to yield to China’s hardball tactics. When its ambassador to China suggested that it would be “great for Canada” if the United States dropped the charges against Ms. Weng, he was fired. Unfortunately, President Trump has undermined that principled position. Twice, including late last month, he has suggested that he might include Ms. Weng’s case in a trade bargain he is trying to conclude with Chinese President Xi Jinping. That would be a gross violation of U.S. legal norms that we hope his new attorney general, William P. Barr, would resist. But the damage is done: No doubt Mr. Trump confirmed the Chinese belief that the case against Ms. Meng is political, and that hostage-taking is an appropriate response.

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