Bitcoin, and probably any other cryptocurrency, uses flooding [1] to propagate transactions. So it would be very difficult to prevent transactions from leaking

Bitcoin, and probably any other cryptocurrency, uses flooding [1] to propagate transactions. So it would be very difficult to prevent transactions from leaking out of or into the isolated zone: A single peer in the whole country which is connected to the outside would be enough to leak all transactions. [1] https://en.wikipedia.org/wiki/Flooding_(computer_networking) https://en.wikipedia.org/wiki/Flooding_(computer_networking)