Trump has justified tariffs on goods from Canada, the top U.S. export market, by accusing it of failing to stop the cross-border flow of fentanyl, even though U.S. government data shows Canada accounts for only 1% of the fentanyl that enters the United States.

The Canadian team working on a trade deal with the United States could walk away from talks in the wake of a U.S. decision to impose a 35% tariff on some goods from Canada, an adviser to Prime Minister Mark Carney said on Friday.

President Trump's tariffs order for countries yet to strike a trade deal with the U.S. went into effect just after midnight on Friday, though most levies aren't due to start until Aug. 7. Why it matters: While countries like Mexico struck trade deal extensions ahead of Trump's deadline,