Yes, there may be no way to avoid it turning into another cycle of measures vs counter-measures. The important thing is to increase the costs and difficulty for the bad guys while decreasing the disruption caused by attacking one cable.

Attaching an explosive to an undersea cable requires trained divers or an ROV, plus at least a little bit of specialized equipment and a few hours to work. It can be done but it's a lot harder than just dragging an anchor.