Sometimes your best mates go a bit mad. Cut them some slack.
They will need a shoulder to cry on when they re-discover how well a trade war works out. The last ones seem to have happened at roughly 50 year intervals.
The US seems to be incapable of learning from the past. The worrying thing is that Mr Trump is old enough to remember directly or what his parents told him about the last fucked up trade shit storm or trade war.
You do not get to dictate how the world as a whole works ... ever. It has its own ideas about that.
Even Britain at its most imperious could not do that and the US can't even stop itself from trying to impose tariffs on its own air base in .io!
The best we can do from outside is to hope that the US does not collapse completely and that the downward trend stops at some point. If, somehow this all pans out that we will all benefit or even that just the US benefits then fine. Let's pick up the pieces and crack on.
I do not hate Americans nor their rather odd President. We are seeing change happening. It might be for the good eventually but I doubt it but I'm not an expert. In the meantime I suggest we continue to act as friends towards an old friend. When you go barking mad, you might need your mates to stand beside you whilst you dribble and widdle.