President Donald Trump's new tariff orders against Canada, Mexico and China all contain clauses suspending a duty-free exemption for low-value shipments below $800 that is widely seen as a loophole that has allowed shipments of fentanyl and its precursor chemicals into the United States.

Drug policy researcher Jonathan Caulkins said there were 21 large fentanyl seizures at the Mexican border for every one along the Canadian border.

Efforts to break up crime syndicates precede threats from the U.S. president, investigators taking down drug labs in Western Canada say.