@briansullivan @lauren More broadly regarding DNS:
If there is an attack on the DNS root through physical infrastructure presence in the US, I would expect rapid action by EU and other nations to establish a new root the rogue US can't touch. This would not alter any contents. Whether the previously US-controlled TLDs would also be forked is less clear, but I'd kinda expect yes.
If there is only an attack on technically US-controlled TLDs, not the DNS root, I think it's less obvious what would happen, but it would likely spark a process of figuring out how the international community would deal with it.