China has vowed to fight to the “bitter end” in a trade war with the US, announcing up to 15 per cent tariffs on American imports.Beijing had threatened to impose countermeasures and reiterated its firm opposition after Trump announced additional 10 per cent levies on Chinese imports.

Canadian and Chinese officials say they were already helping reduce fentanyl smuggling. Prime Minister Justin Trudeau said fentanyl crossing the northern border is "near zero."