The most notorious attack was the September 2022 attack on the Nord Stream pipelines near the Danish Island of Bornholm in the central Baltic Sea. No entity has conclusively been attributed to the attack that damaged elements of both Nord Stream 1 and 2, as major investigations are still ongoing. The attack underscored the vulnerability of underwater critical national infrastructure (CNI) while also highlighting the challenges in repairing, policing, and attributing incidents.

Suspected incidents of undersea sabotage, notably in the Baltic Sea, have further illustrated these challenges in 2023. In October, there was a significant decrease in pressure in the “Baltic Connector,” an underwater gas pipeline linking the gas networks of Finland and Estonia. An explosion may have caused this drop in pressure. Additionally, an unspecified location sustained damage to a telecommunication cable between the two countries.

Although conclusive evidence is lacking, suspicions indicate deliberate damage in the Baltic was likely due to hostile state activity. Most accusations point to Russia, which almost certainly possesses the capability and intent to sabotage subsurface CNI.