The letter circulated by Huawei Technologies Co. was blunt. Canada was becoming dangerously entangled in the diplomatic feud between Washington and Beijing, it said, and there was only one answer: for Justin Trudeau’s government to free the state-championed tech giant’s chief financial officer and let her go back to China.

It sounds like a warning from the Chinese government. In fact, the June 23 letter to the prime minister was signed by a who’s who’s of 19 prominent Canadians — among them a retired Supreme Court justice, a former attorney-general and several ex-Cabinet ministers and ambassadors. Within 24 hours of it making headlines in Canada, Huawei executives were sharing the four-page note with journalists abroad.

The letter was meant to propose an answer to the plight of two Canadian men who’ve been accused by China of espionage and whose grim captivity for more than 18 months has left the nation aghast. Instead, it appears to have hardened Trudeau’s resolve, backed by an electorate that’s no longer in a mood to see the government cut deals with Xi Jinping.