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.

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 special appellate court is weighing Trump's challenge to a decision by a federal trade court to throw out his tariffs because they exceeded his authority, but its "decision could be weeks away," The Washington Post said. The case is ultimately "expected to end up at the Supreme Court."