President Donald Trump has justified tariffs on Canadian imports by citing a flood of smuggled fentanyl. But nearly all of the powerful opioid is smuggled from Mexico.

Canadian and Chinese officials say they were already helping reduce fentanyl smuggling. Prime Minister Justin Trudeau said fentanyl crossing the northern border is "near zero."

Former central bank chief Mark Carney was sworn in as Canada’s prime minister on Friday, taking over at what he has called “a time of great peril” as the country faces a trade war with the United States and annexation threats from President Trump.