Okay, let's assume most of their steel is Chinese (I have my doubts because, yet again, more conspiracies), we only import a quarter of the steel we use. That would hurt losing it overnight, sure, but we wouldn't be absolutely toast like the autarkists are saying.

These takes are much more doomer than I'm willing to bet the supporters of "bring everything back" realize. Do you have no faith in the US economy / populace adapting to a hypothetical all out war with China?

I have a feeling that China doesn't export much steel. They more likely export their steel in the form of finished products.