It's worth mentioning that cable breakages happen quite often; globally about 200 times per year [1] and the article itself mentions that just last year, two other cables and a gas pipeline were taken out by an anchor. The Gulf of Finland is evidently quite shallow. From what I understand, cable repair ships are likely to use ROVs for parts of repair jobs but only when the water is shallow so hopefully they can figure out whether the damage looks like sabotage before they sever the cable to repair it. Of course, if you're a bad actor and want plausible deniability, maybe you'd make it look like anchor damage or, deliberately drag an anchor right over the cables.

Cable repairs are certainly annoying and for the operator of the cable, expensive. However, they are usually repaired relatively quickly. I'd be more worried if many more cables were severed at the same time. If you're only going to break one or two a year, you might as well not bother.

1: https://www.theverge.com/c/24070570/internet-cables-undersea...

> Joint statement by the Foreign Ministers of Finland and Germany on the severed undersea cable in the Baltic Sea

> We are deeply concerned about the severed undersea cable connecting Finland and Germany in the Baltic Sea. The fact that such an incident immediately raises suspicions of intentional damage speaks volumes about the volatility of our times. A thorough investigation is underway. Our European security is not only under threat from Russia‘s war of aggression against Ukraine, but also from hybrid warfare by malicious actors. Safeguarding our shared critical infrastructure is vital to our security and the resilience of our societies.

https://www.auswaertiges-amt.de/en/newsroom/news/-/2685132

And also the cable between Lithuania and Sweden:

https://www.theguardian.com/world/2024/nov/18/telecoms-cable...

Substantial Russian activity also near UK, raises concerns that Russia would cut off UK. [0]

Russian ships ‘plotting sabotage in the North Sea’ [1]

[0] https://www.independent.co.uk/news/uk/home-news/uk-undersea-...

[1] https://www.independent.co.uk/news/world/europe/russia-ships...

So what's the solution ? Assign a surveillance UAV to every Russian ship parked "without a good reason" over a cable ? It would be expensive, but doable, and create a reserve of vehicles for wartime use.