TORONTO — Roughly $900 billion in annual trade between Canada and the United States — and with it, traditionally chummy bilateral ties — is on the brink of upheaval, with President Donald Trump threatening to impose sweeping tariffs on Canada as early as this weekend.

U.S. President Donald Trump has pledged to place 25% tariffs on imports from Mexico and Canada from Feb. 1 if the two countries are not judged to be doing enough to stop the flow of fentanyl into the United States.

General Motors, the largest producer of cars in Mexico, won’t provide details on how it would react if President Trump imposes 25 percent tariffs from the two countries.