How is the US getting away with these tariff policies given WTO rules on Most Favoured Nations?

As I understand it, the WTO requires that states treat all other members equally as far as tariffs are concerned, unless they have an FTA.

I appreciate that enforcement of this is impossible, but has the US given even a fig leaf of justification for abandoning this completely and charging massive tariffs on specific nations it has a grievance with while offering exemptions to others?