1) Rapid identification and localization of breaks, so military/police forces can be dispatched to the area.
2) Continuous deployment of MQ-9B SeaGuardian or HALE UAV platforms around shallow cable runs to locate and id dark ships, who would also be running nav beacons before and after.
3) Low-earth-orbit persistent sensing networks (e.g. what's now called PWSA [0]) with ship id'ing sensor packages.
As parent notes though, the lynchpin of this is inverting the cost:benefit ratio to be unfavorable, by raising the likelihood that ships will be detained and ultimately seized.
Even oligarchs don't like to light money on fire.
[0] https://spacenews.com/space-force-preparing-for-the-age-of-p...
