[mort96]

What rules? Is the US not subsidising its own industry?

[riku_iki]

The question is to what extent. Both US/EU and WTO have anti-dumping rules.

[mort96]

Has China been ruled to be in violation of those rules?

[riku_iki]

Sure, both US and EU run multiple investigations.

While in US, potus can impose tariffs at whim, until scotus decides otherwise, my understanding is that EU tariffs are results of such rulings.