In the silent depths of the Baltic Sea, the unseen arteries of modern life (submarine cables) sustain the pulse of digital and energy networks. They transmit 95% of the world’s internet traffic, enable financial transactions worth trillions, and power cross-border energy flows essential for Europe’s stability.
Since 2022, the Baltic region has become a theater of increasing maritime tension. At least six suspected acts of sabotage have been recorded in its waters, affecting 11 undersea cables since 2023 alone. These incidents are not isolated anomalies but signs of a broader pattern. As the global balance of power recalibrates, undersea infrastructure has emerged as a new frontier in hybrid warfare.
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The Baltic Sea: A Geopolitical Flashpoint
The Baltic Sea has become increasingly volatile, with rising tensions between North Atlantic Treaty Organization (NATO) member states and Russia. Bordered by several NATO countries—Estonia, Latvia, Lithuania, Poland, Germany, and Denmark—the sea also encompasses Russia’s heavily militarized Kaliningrad exclave. Since early 2025, Russian forces have stepped up naval operations, including extensive military exercises involving hypersonic missiles off the coast of Kaliningrad, highlighting the area’s strategic importance and vulnerability amid escalating tensions between Russia and NATO.
Over the past fifteen months, at least 11 undersea cables in the Baltic region have been damaged under suspicious circumstances. Naval intelligence has linked several of these cases to hostile reconnaissance, including the Russian ship, Yantar, operating near British waters. In response, the Royal Navy surfaced a submarine in a clear show of deterrence. Meanwhile, Swedish authorities are investigating sabotage on undersea cables connecting Germany and Finland.
Furthermore, in November 2024, two submarine telecommunication cables—the BCS East-West Interlink and C-Lion1—were disrupted in the Baltic Sea. The incidents occurred near-simultaneously and nearby, prompting accusations from European officials and NATO member states of hybrid warfare and sabotage.
The convergence of increased Russian military activity, suspected sabotage incidents and emerging technological threats underscore the Baltic Sea’s status as a geopolitical flashpoint. As Europe grapples with these challenges, the protection of undersea infrastructure has become a paramount concern for regional security and stability.
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Europe’s Strategic Response
Recognizing the gravity of the situation, European nations and institutions have begun to take decisive steps. On April 14, 2025, Estonian President, Alar Karis, approved significant legal amendments granting the Estonian Defence Forces (EDF) the authority to take action against vessels threatening critical underwater infrastructure, including cables and maritime assets. The amendments, which expand the Estonian Armed Forces Organization Act and laws governing the nation’s economic zone, empower the military to act preemptively against vessels jeopardizing Estonia‘s national defense and vital services. The new legislation allows the EDF to respond to threats within Estonia’s maritime zone, broadening its scope of enforcement.
During the same month, Denmark announced a significant defense investment of approximately USD 614 million to build and procure 26 specialized naval vessels. This initiative is part of the country’s broader defense strategy, which includes a 10-year defense budget of DKK 190 billion to address modern maritime threats, particularly those emerging from Russia. The newly procured vessels will enhance Denmark’s ability to patrol key maritime routes, respond to oil spills, and monitor undersea cables and critical infrastructure. The expansion plan includes four multifunctional environmental protection and mine-laying vessels, a specialized ship equipped with drones and sonar for underwater surveillance, and 21 new vessels for the Naval Home Guard.
The European Union (EU), acknowledging the systemic nature of the threat, has introduced the EU Action Plan on Cable Security. This initiative aims to build resilience across four key pillars: prevention, detection, response and recovery, and deterrence. From 2025 to 2027, an additional EUR 540 million will be directed toward strengthening digital infrastructure, including securing undersea networks. This funding will support advanced surveillance systems, cross-border incident response coordination, and real-time threat monitoring technologies.
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The Role of Technology and International Cooperation
Today, Europe’s efforts to safeguard its undersea infrastructure have intensified, driven by a rise in sabotage incidents and mounting geopolitical tensions. These developments have spurred a more cohesive and technologically advanced response across NATO and its partners.
One of the most significant developments has been the launch of Operation Baltic Sentry by NATO. Coordinated by the Joint Forces Command in Brunssum, this mission unites maritime forces from Germany, the Netherlands, France, and Estonia. It integrates unmanned surface and underwater vessels into Baltic Sea patrols, supported by the UK-led Joint Expeditionary Force’s Nordic Warden AI system, which analyzes maritime activities in real time to detect threats.
Recognizing the strategic vulnerability of its waters, Ireland has begun reconsidering its long-standing neutrality. With 75% of Europe’s internet traffic crossing through Irish-controlled undersea cables, the country faces mounting calls to strengthen its maritime surveillance and cyber defense systems.
The European Commission has also moved to reinforce the protection of critical undersea infrastructure, announcing a series of updated directives. These include stronger security protocols, mandatory risk assessments, and frameworks for rapid coordinated responses among member states.
On the technological front, NATO has been testing the innovative Task Force X program in the Baltic Sea. These uncrewed naval drones, designed for endurance patrols and real-time threat detection, represent a significant leap forward in securing maritime assets.
Securing the Lifelines of the Digital Age
The undersea cables crisscrossing Europe’s maritime domains are more than mere conduits of data and energy; they are the lifelines of the digital age. Protecting them requires a concerted effort that blends legal reform, technological innovation, international cooperation, and strategic investment. As the continent navigates the complexities of modern hybrid threats, the resilience of its undersea infrastructure will be a testament to its commitment to security, sovereignty, and the seamless flow of information and power.
But resilience cannot rely on governments alone. With over 95% of these cables owned by private entities, sustained collaboration between state actors and tech giants is critical. The rapid militarization of deep-sea capabilities, including autonomous submersibles and cable-cutting technologies, adds a new layer of complexity to maritime defense. A single, well-placed act of sabotage could ripple across continents, halting stock exchanges, crippling cloud services, or blacking out power grids. The stakes are no longer regional; they are global. Europe’s vigilance today may well define the stability of tomorrow’s connected world.
