Mad King Donald threatened Canada with 35% tariffs in an unhinged letter that eventually cites fentanyl as a problem when less than 1% of fentanyl seized originates in Canada, challenging Canada to solve a problem that does not exist.

To be fair, this is not necessarily a sign of Trump being out of it. It's more likely just the Administration trying to defend the tariffs against legal attacks.

As has been noted (and held in the court of international trade case), Congress has the power to set tariffs. The President doesn't have inherent tariff-setting authority. He only has the tariff powers that are delegated to him by Congress.

The President wants to raise tariffs because that's the trade policy he wants to implement - but most of his tariff-setting authority is limited to things like emergencies or border control. So even though his tariffs are driven by his economic policy preferences, he doesn't really have the power to decide what tariffs should be imposed for general economic or trade reasons. So these tariffs are on very shaky legal ground.

Which is why the pronouncements have tended to include fentanyl, or border control, or some other factor aside from trade deficits. That way the Administration can point to them in court and claim that he's exercising a delegated authority to impose tariffs.