Quoted from Bublehead:You either help out the domestic auto production by removing tariffs, or you keep steel prices high and force jobs to move to lower wage countries to help balance the increase in production costs.
Another perspective is that we need to take a long term view to protect US economic competitiveness and jobs and make difficult strategic choices - and ensure we don't have to depend on anyone at the end of the day in an uncertain world to build our tanks and ships. Doubt GM decided to rationalize its product line and workforce base on a snapshot of the current political/trade environment. Other US based car manufacturers seem to be adapting better.