Tariffs
Start with Trump being a #Genius and the amounts and the way those amounts were arrived at don't surprise or even look unusual.
From here that's a dominance display - Trump showing all the other players that their expectations that he'll be bound by norms, treaties, tradition, reason and logic are useless fantasies.
"I can do whatever the fuck I want, and you can't know what I'll do next. I'm #Unpredictable and you're all piss-weak."