Many years ago, American industry manufactured pretty much every thing we needed.  But then, we found we could buy and import a lot of items like steel and autos, and etc. cheaper from foreign countries.

This was taking business away from American companies, so we imposed import tariffs on those companies which caused their prices to increase by the amount of the tariffs. This put their prices in comparative balance with our prices. This worked well because it leveled the price competition.

But now we do not build the items we import, so tariffs added to the imported prices only increase the final price. Because there is no price competition, the tariffs provide no value to us Americans.  Just higher prices.

I hope this helps explains the futility of imposing import tariffs when we are not protecting our own manufacturing.