At least one .org website that I know of has been shut down because the USA pressured the US organisation that controls the .org domain into doing so.
They could repeat this at will for quite a number of sites.
An immediate step to prevent this possibility, if you run a website, is to register a domain that is controled outside the US.
I have not found one article that just lists them all, and who controls them, but most TLDs have their own wikipedia article, e.g. .org (US controled), .eu (not US controled, yay) etc.
Ultimately ICANN controls all of this, and that's a US orga too, and Trump could bully them into doing shit, too. But the people who know about these things don't seem to think that's a likely threat right now. Also ICANN seems to defer a lot of tasks to exactly these TLD orgas. After all the internet still is (somewhat) decentralized.
it is the name servers that are spread around the world
But the nameservers get their lists from elsewhere - i.e. PIR in this case - and while it's technically possible to amend these lists, they don't typically do so. The few that do, just add a few tlds, but don't edit existing entries in the lists they get.
But I agree that is something the rest of the world will need to look into rather sooner than later.