Yes, you've just described one method the US authorities use to block websites.

They also force ISPs to block IPs [0].

I feel trying to say that's not "blocking websites" is playing games with words, and the results are functionally the same to the "average" user.

The fact that the US effectively claim juristiction over the root DNS system is a more a geopolitical power thing rather than a legal restriction.

[0] https://torrentfreak.com/us-court-orders-every-isp-in-the-un...