The imbalance in President Trump’s treatment of America’s closest trading partners may come from his desire to make Canada the 51st state, some Canadians believe.

Trump has justified tariffs on goods from Canada, the top U.S. export market, by accusing it of failing to stop the cross-border flow of fentanyl, even though U.S. government data shows Canada accounts for only 1% of the fentanyl that enters the United States.

President Donald Trump has raised the tariff rate on U.S. imports from Canada to 35% from 25%, effective Friday. The announcement from the White House late Thursday said Canada had failed to “do more to arrest,