Ya think? It will cost the US billions in rising costs and lost employment. Many companies import steel and machine it or roll it to sell in the US. a 25% tariff either moves production to Canada or more likely just eliminates the local US manufacturing base that makes bearings, shafts etc. For the rest of us it raises costs of cars and white goods etc so it may also become more economical to import the finished product.
But the whole thing was simply a diversion to make sure that no one talked about the TPP that was signed by 11 countries - no USA to improve trade between themselves and the US is excluded because the Moron in Chief thinks he can do better deals than anyone else on the planet and completely missed the point of TPP which was designed (not well I might add) to reign in China and increase sales of US goods and services.
Never mind, we can eat "beautiful clean coal" while China has a plan to dominate new technologies. Makes you wonder.