OTTAWA, Aug. 24 -- The assembly lines in Windsor have run without interruption for longer than most of the workers on them have been alive. Sunday's announcement may change that. After weeks of talks that Prime Minister Mark Carney described as producing "important progress," Washington walked away, and then turned around with a threat: 50 percent tariffs on Canadian automobiles and steel, effective January.

Trump posted to Truth Social that "Canada wants the benefits of being a State, without being one!!!" The three exclamation marks were the full extent of the economic analysis on offer.

Trump's administration imposed the duties on approximately $20 billion in Canadian goods after negotiations collapsed Sunday. The affected products s...