A tariff on steel imports causes the price of imported steel to increase. One direct effect is:
The Mid-Continent Nail plant in Poplar Bluff, Missouri, laid off 60 of its 500 workers last week because of increased steel costs. The company blames the 25% tariff on imported steel. Orders for nails plunged 50% after the company raised its prices to deal with higher steel costs.
UPDATE: I'm adding this to our new "It's easy to win a trade war' category, as soon a John gets around to updating our category list.