Who determines who owns a domain name? International organization? Do unrecognized countries also get their own top-level domain? If someone or some organization wanted to register a website for highly illegal activities (terrorism, crime organizations, etc) who has the authority to shut them down? Does one government has the authority, or does it require a majority of the countries? What if, say, North Korea hosted a website advocating terrorism? Who can take that down?
The physical location of the registrar plays a role in who had authority. There’s also the location of the site itself to consider, though that’s harder with things like cloud hosts or the TOR network. It’s also possible that a government could require all ISPs in their country to redirect or sinkhole the requests from their users, but that leaves the door open for end users to change their DNS provider.
Short version, it depends. There are a lot of variables in play and levers to pull.