Having AIS on is mandatory. I'm sure turning it off would raise even higher warning flags than just leaving it on while doing your shady stuff.
Regardless, there are satellites covering the area, so you wouldn't get rid of being tracked anyways, would just be a bit slower.
Having AIS on is mandatory, and in many places taken quite seriously. Last night we sailed from Fuerteventura to Gran Canaria. There was a cargo ship with broken AIS in the area, and the VTS broadcasted their position over VHF every half hour (with DSC all ships alarms and everything)
Every recreational sailor knows that AIS is "mandatory." It's completely routine to see commercial ships running without it.
recent statistic : Global Fishing Watch’s study published in Science Advances on November 2, 2022, revealed that:
Over 55,000 suspected intentional disabling events of AIS signals were identified between 2017 and 2019, obscuring nearly 5 million hours of fishing vessel activity. This phenomenon accounts for up to 6% of global fishing vessel activity.
Having AIS on is mandatory, but in practice a lot of ships turn it off regardless. From shadow oil fleets laundering sanctioned oil to fishermen, fake or disabled AIS systems are hardly an exception.
I don't think Russia is trying to hide their sabotage, though. Even with AIS disabled, there's no way European intelligence agencies didn't know what ships were floating above these cables at the time they went down.
This was a warning, not a secret operation.