At least some of these are accidental, because ships have damaged cables for a long time. Europe’s stopped several ships that have caused damage, had physical access to the ship, and I have yet to heard of one where law enforcement actually wound up saying “we conclude that this was an intentional cut”.

There have definitely been cases where important people have said that they believe that cuts are intentional, but those were not speaking of situations where their investigators had actually come to that conclusion after looking at the ship in a specific incident and asking questions of the crew:

https://www.cnn.com/2024/11/20/world/accident-or-sabotage-undersea-cables-intl/index.html

European leaders were quick to voice their suspicions. Germany’s Defense Minister Boris Pistorius said that “nobody believes that these cables were accidentally severed.”

The foreign ministers of Finland and Germany said in a joint statement that they were “deeply concerned” about the incident and raised the possibility that it was part of a “hybrid warfare,” specifically mentioning Russia in their statement.

Their assessment was not plucked out of thin air. Russia has been accused of waging a hybrid war against Europe after a string of suspicious incidents, arson attacks, explosions and other acts of sabotage across multiple European countries were traced back to Moscow.

And the disruption to the cables came just weeks after the US warned that Moscow was likely to target critical undersea infrastructure. This followed months of suspicious movements of Russian vessels in European waters and the significant beefing up of a dedicated Russian secretive marine unit tasked with surveying the seabed.

But two US officials familiar with the initial assessment of the incident told CNN on Tuesday the damage was not believed to be deliberate activity by Russia or any other nation.

Instead, the two officials told CNN they believed it likely caused by an anchor drag from a passing vessel. Such accidents have happened in the past, although not in a quick succession like the two on Sunday and Monday.

The Kremlin on Wednesday rejected the “laughable” suggestions that it was involved, saying it was “absurd to keep blaming Russia for anything without any grounds.”

I can’t find much by way of a graph of submarine cable severing frequency by year, but this (which only shows older years) at least does illustrate that this isn’t a new phenomenon:

https://www.researchgate.net/figure/Summary-of-the-causes-of-submarine-cable-faults-attributed-to-external-aggression-as_fig1_224378640

https://iscpc.org/publications/icpc-viewpoints/damage-to-submarine-cables-from-dragged-anchors/

Damage to submarine cables from dragged anchors account for approximately 30% of incidents each year representing around 60 faults. Damage to these cables is costly, with telecommunication repairs averaging £500k-£1m per incident and power cable repair costs reported to be in the region of £10m-£100m per incident depending on many variables. Downtime from cable damage has the potential to cause disruption to global communications and energy transmission and distribution.

• One of the most significant anchor drag events in recent history occurred off Sicily in 2008, where a ship dragged its anchor for 300 km, damaging six submarine cables. Such incidents can disrupt multiple cables in proximity, magnifying the impact of an event2 [?].
• Another example is the incident between the Channel Islands and Cornwall, UK where a vessel deployed anchor in poor weather, causing damage to several telecommunications cables3 .
• There was another incident on 17 March 2016 where a vessel dragged its anchor causing damage to telecommunications cables and a power cable, which cut off the electricity supply to the Isles of Scilly4 for a significant period of time.
• The Chilean flag container ship Aconcagua cut three of the then 4 cables linking the United States to Europe in 2002 while sailing from Philadelphia to New York City. The captain erroneously attributed the reduction in the ship’s speed during a gale to the wind when in fact it was the ship’s anchor dragging. Investigation revealed that the anchor windlass had only been secured with the brake and the chain stopper had not been used.
• The Liberian flagged vessel Blue Princess damaged three submarine cables in the Red Sea in 2012. Over a period of 12 hours on 17th February 2012, SEA-ME-WE 3, EASSy, and EIG, causing multiple cable faults. The vessel could be tracked using AIS as crossing the cables at a similar time as faults were reported and appeared to become fastened to the cable with the speed reducing to zero at the time of the final fault during that period.

This is not in any way to discount the possibility that a state could intentionally attack submarine cable infrastructure, which is vulnerable. In the past, cutting cables has been a feature of wartime activity. We have linked Russian intelligence to a set of arson attacks in Europe, so it’s not as if there isn’t a willingness to cause damage. But (a) ships do regularly cause damage to submarine cables and (b) there hasn’t yet been a smoking gun indicating that an investigated cut that has occurred has been intentional.

I get an incredulous “how do you manage to haul your ship’s anchor for hundreds of kilometers and through a number of submarine cables without noticing? What kind of captain are you?” But…people have managed to do so in the past.