They'd need to run a VPN with end point in a less hostile country and so there's an element of enforcement on those endpoints.

At any rate, blocking China and Russia isn't ever presented as a foolproof defence, it just raises the barrier to attack.

They extensively use these VPNs, in NL. They can also use Tor exit node.

Either way, nothing is full proof. It is part of a solid defense in depth [1].

[1] https://en.m.wikipedia.org/wiki/Defense_in_depth_(computing)