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."

Prime Minister Justin Trudeau of Canada warned that the Trump administration’s tariffs were leading to a trade war. Mexico’s leader vowed to impose countermeasures on Sunday.

The action immediately shook global markets, plummeted stocks and will likely raise prices on everyday products – from gas to produce – for consumers. Canada, Mexico and China quickly retaliated, with Canadian Prime Minister Justin Trudeau saying Ottawa is setting 25% tariffs on $20.7 billion worth of U.S. imports, from orange juice to cosmetics.