[gthtjtkt]

> And why is that a problem, exactly?

It says in the article: American companies are being put out of business by heavily-subsidized Chinese companies.

> Trying to enforce a tariff on element production from a subset of external countries seems sisyphean.

Apparently not:

> The company failed to obtain NAFTA benefits after U.S. authorities concluded that the metal came from China.

It helps to read the article you're commenting on ;)

[JoeAltmaier]

But there are essentially no tariffs any more. Not sure how NAFTA changed that. But assuming its true: aluminum is fungible as mentioned. Providing more to Mexico means they can export more of their own to the US.