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.

President Trump’s long-threatened tariffs against Canada and Mexico went into effect Tuesday, putting global markets on edge and setting up costly retaliations by the United States’ North American allies.

The tariff actions, which could upend nearly $2.2 trillion in two-way annual U.S. trade, went live hours after Trump declared that all three countries had failed to do enough to stem the flow of the deadly fentanyl opioid.