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."

After a fresh wave of tariffs from the United States, Canada and the European Union said they would impose billions in levies on U.S. goods.