What is the cyber equivalent of 'use of force'
That has a very simple answer. De-peer the country - mandate all ISPs to filter out any route announcements from it.
By the way, Russians with their new critical infrastructure legislation can do that. Their new laws deem peering points critical infrastructure in addition to all transit SPs. The state can order them to filter out a particular autonomous system or network range.
We should simply do the same. It is the Internet equivalent of calling in the tanks.