U.S. tariffs on Canada have put experts at odds over how appropriate the action was, particularly given the unaddressed demand side of the fentanyl epidemic.

White House economic adviser Kevin Hassett said on Sunday he was hopeful a dispute with Canada over accusations of the deadly fentanyl opioid entering the U.S. across its northern border could be resolved by the end of March.

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."