Underwater attack on European subsea infrastructure: Intrusive maritime operations undermining European undersea assets
In recent times, Europe has found itself at the centre of a complex geopolitical web, with the Baltic Sea and its infrastructure assuming particular strategic importance. This region, situated between Russia and key members of NATO and the EU, has become a focal point of concern due to a series of incidents involving undersea cable damage and Russian oil shipments.
The Baltic Sea, with an average depth of 52.3 meters, and the North Sea, at 95 meters, are vulnerable to cable severance by anchors, making their undersea infrastructure a potential target. Since October 2023, at least 11 cables in the Baltic have been damaged, with investigations suggesting possible Russian sabotage.
Europe's response to these threats has been multi-faceted. In January 2025, NATO launched Baltic Sentry, a mission aimed at strengthening maritime presence and surveillance in the Baltic Sea. Simultaneously, European leaders and intelligence agencies have emphasised the need for assertiveness in deterring threats to critical infrastructure.
In February 2025, the EU introduced its own Subsea Cable Security Action Plan. This plan focuses on several key areas, including the prioritisation of mapping existing and planned undersea infrastructure to prevent connectivity and security disruptions. The EU also seeks to hold those responsible accountable through effective attribution, such as forensic analysis.
Moreover, Europe should avoid over-reliance on a single gas pipeline or data cable and require companies to develop backup systems. To increase costs for hostile actors, the EU can tighten enforcement of sanctions, eliminating loopholes and preventing Moscow from maintaining significant revenues.
The undersea cables in the Baltic Sea carry approximately 97% of global internet traffic and a significant portion of government communications. They also transmit approximately $10,000 billion in daily financial transactions. The disruption of these cables could have catastrophic consequences for Europe's economy and security.
China's Silence Ocean company has introduced a new subsea device capable of cutting undersea cables to a depth of 4,000 meters. While it is unclear if this technology has been employed in the Baltic Sea, it underscores the need for Europe to be vigilant and proactive in protecting its undersea infrastructure.
The Baltic Sea states also have the power to impose stricter controls on Russian oil shipments. They can declare a "special period" and temporarily suspend certain maritime laws, providing a powerful tool for deterring potential threats.
As the situation in the Baltic Sea continues to evolve, it is clear that Europe must act decisively now to prevent far greater threats tomorrow. This includes better utilisation of existing surveillance tools, strengthening international intelligence cooperation, and ensuring a diversified energy and communication infrastructure. Failing to do so could leave Europe vulnerable to potential sabotage and economic disruption.
