It's not just about a tariffs war bringing to an end the free-market world of the last 40 years which, on the whole, made the whole world richer.
What we are beginning to see amongst Usofa's traditionally closest friends & allies - the Europeans, Oz, Japan ... - is a process just getting under way of disengaging from doing business with Usofa in important areas such as defence & security, on the basis that you can't trust the Yanks any more. Macron, for instance, is busy persuading the Europeans not to buy the F35 (which means switching to French or Swedish alternatives). The boycotting of Tesla products is another obvious example, with public outbreaks of contempt and anti-Usofanism.
This will continue gradually gathering speed. Short of major backtracking by Trump (not in his genes, I think), the long-term damage to the Usofan economy will be great indeed.