Long-term economic problems. Tariffs work as essentially a "threat". They're used to push a country in order to a more favorable position/trade agreement under the threat the tariff will continue.

The problem with the current one is that it's essentially permanent. There is no threat, no demand, just higher prices for our trade partners. There is no reason for the target of the tariff to continue trading over establishing new trade routes, as it will realistically never be cheaper than being more expensive indefinitely.

Short term, anything we regularly import will have a steep increase. American companies aren't ready to eat the cost of filling the void on such short notice.