President Trump on Thursday threatened to impose a 35% tariff on Canadian goods beginning Aug. 1. Mr. Trump's latest salvo came after he also threatened tariffs on a number of other countries earlier in the week,

Many countries thought they were negotiating in good faith. The White House renewed its “reciprocal” tariff plan anyway, giving countries until Aug. 1 to make offers.

Trump’s move deepens a rift between two North American countries that have suffered a debilitating blow to their decades-old alliance.