Hidden lifeline of digital Nordics

For the Nordic region, these cables are more than a technical asset. They are a hidden lifeline, working in tandem with the terrestrial networks, that sustains economic activity, secures defence communication, and ensures citizens remain connected to the world. But in an era marked by growing geopolitical conflict and increasingly complex hybrid threats, this underwater infrastructure is coming under renewed scrutiny. The same cables that make Nordic societies resilient also represent some of their most attractive targets.

Analysts at the Centre for Strategic and International Studies (CSIS) warn that these global connections are now central to great-power competition, making them increasingly attractive targets for disruption. For the Nordics, which sit at the intersection of transatlantic and Eurasia data routes, the resilience of subsea cables has become a matter of both national security and regional stability.

Cloud services and satellite communication provide some degree of redundancy, but their role is mostly complementary. Satellites can offer a fallback when cables are compromised, yet their capacity remains below what fibre-optic systems deliver. Emerging satellite-to-phone solutions are expected to play a complementary role in ensuring resilience, particularly in rural areas or during outages when terrestrial infrastructure is unavailable. However, the lesson is clear: for the Nordics to remain fully connected, competitive, and secure, the integrity of subsea cables must be safeguarded.

The cables that carry the digital lifeblood of the Nordics are a little thicker than a garden hose, yet they carry the capacity to transmit terabits of data every second. Near shore and in shallow waters, they can be ploughed into the seabed or protected with layers of steel armouring to guard against anchors, fishing gear, and other human activity. In the deep ocean, burial is usually not possible, so cables are placed directly on the seabed where they are relatively safe from interference but still exposed to natural hazards such as undersea landslides or earthquakes. At the points where cables come ashore, special attention is paid to reinforcement and monitoring, since landing stations remain among the most critical and vulnerable points in the entire system.

The Baltic and North Sea have already experienced serious incidents. In 2024, two cables – C-Lion 1 between Finland and Germany, and the BCS East-West Interlink between Sweden and Lithuania – were damaged within days of each other. Investigators found strong signs of tampering, highlighting the vulnerability of this infrastructure at a time of heightened geopolitical tension. The same year, Finnish authorities accused a foreign vessel of damaging both a gas pipeline and a communication cable in the Gulf of Finland, a sign of how energy and digital infrastructure are increasingly linked as targets.

These events illustrate the new reality: in times of conflict, subsea cables may be among the first assets to be targeted. However, the threat is not only to the assets on the seabed. Cable landing stations and the management systems that control them are also potential entry points for threat actors. As digital warfare becomes more advanced, the distinction between a physical cut and a cyber-enabled disruption is increasingly blurred.

The vulnerabilities exposed in recent years have prompted a series of protective measures at European, transatlantic, and national levels. What was once an obscure technical concern has now become a known matter of security and resilience.

In February 2025, the European Union introduced its Action Plan on Submarine Cable Security. The European Commission described it as “a comprehensive plan to enhance the resilience of submarine and energy cables, covering both communication and electricity infrastructure”. The plan organises its measures around four pillars: prevention, detection, response & repair, and deterrence. Among its priorities are investments in smarter, redundant cables, the creation of an EU reserve fleet of repair vessels, and new financing mechanisms to speed up infrastructure upgrades. Just as importantly, the plan emphasises operational coordination across the member states, recognising that a cut in one part of the network can have cascading effects far beyond national borders.

Henna Virkkunen, Executive Vice-President for Tech Sovereignty, Security and Democracy for the European Commission, said, “In response to growing geopolitical tensions, particularly in regions such as the Baltic Sea, the European Commission is taking decisive action to safeguard our critical submarine cable infrastructure. With this Action Plan, we are taking a significant step forward to strengthen their security. We want to make sure Europe is equipped not only to prevent and detect sabotage to cables but also to actively deter, repair and respond to any threat to critical infrastructure that is key to our economy and collective security.”

Security at sea is also being strengthened through NATO. With Finland and Sweden now in the alliance, the Baltics and North Atlantic have become priority areas for surveillance. NATO has expanded patrols using ships, aircraft, and other unmanned systems to monitor activity near critical infrastructure. Discussions are also underway about establishing dedicated emergency fleets that are capable of rapid cable repairs in case of disruption.

Alongside maritime patrols and cable repair fleets, there is also growing recognition of the role satellites and cloud can play in resilience planning. Integrating satellite connectivity into civil contingency frameworks for instance, to support emergency communications, government continuity, and basic service provision, provides an additional line of defence if subsea or terrestrial networks are disrupted. At the same time, ensuring that critical workloads are hosted in resilient and regionally distributed cloud infrastructures can reduce dependency on single transatlantic routes and enable continuity even in the face of major disruptions.

On a broader European cybersecurity level, the EU’s official Agency for Cyber Security (ENISA) has issued guidance to improve resilience. It highlights the risks of cable landing stations and management systems, which can be digitally targeted even if the physical cables remain intact. ENISA stresses the need for stronger information sharing, cross-border coordination, and technical standards that integrate both physical and digital defences.

The European Commission has also set up an informal Submarine Cable Infrastructure Expert Group. This group, composed of Member State authorities and EU agencies (with input from bodies such as ENISA), is intended to complement the previously mentioned EU Action Plan on Submarine Cable Security by supporting implementation of its four resilience pillars (prevention, detection, response, recovery, and deterrence). Among this Expert Group’s roles are facilitating rapid information exchange across capitals and Brussels, as well as maintaining an up-to-date map of submarine cable networks across Europe, and rolling these updates into annual resilience planning cycles. Its work serves as the structural backbone of broader actions, such as risk mapping and Cable Projects of European Interest (CPEIs), as well as the development of unified resilience strategies under the EU Action Plan on Submarine Cable Security.

Regional initiatives are also taking shape. The NorthSeal security platform operationalises the Joint Declaration on cooperation to protect critical subsea infrastructure in the North Sea, signed by Belgium, the Netherlands, Germany, Norway, the UK, and Denmark on 9 April 2024. By combining surveillance resources and sharing intelligence, NorthSeal aims to reduce response times and strengthen deterrence in one of Europe’s most critical maritime zones. As Norwegian Minister of Energy Terje Aasland emphasised during the signing of the Joint Declaration: “Together with our neighbours around the North Sea basin, we share a common interest to safeguard our critical infrastructure. This is crucial both in terms of energy security and resilience, and to ensure the safety of those who work offshore. The collaboration of signing this Joint Declaration is a necessary foundation for maintaining overall security and strong evidence of our shared interests. Together, we are stronger.”

Nordic national security agencies share these concerns. The Norwegian National Security Authority (NSM), in its Risk 2025 assessment, warns that “sabotage attempts in Norway are likely” and underlines that “equally important to protective measures is ensuring backup solutions and robust repair capability.” NSM stresses that this applies directly to critical infrastructure such as subsea cables and pipelines.

The Norwegian Police Security Service (PST), in its National Threat Assessment 2025, states that “so-called proxy actors are being used by more states” and notes that Russian intelligence has already carried out “dozens of sabotage actions and disruptive activities using proxy actors” in Europe. While PST’s report does not mention subsea cables specifically, its warning reinforces the heightened sabotage risk to Norway’s critical infrastructure.

On the Swedish side, the Swedish Security Service (Säkerhetspolisen) has documented incidents of cable breaks in the Baltic Sea as part of hybrid threat activity against infrastructure. Sweden’s national risk and vulnerability assessment also highlights sabotage of underwater infrastructure, including subsea cables, as particularly difficult to monitor and protect. This concern was heightened in November 2024, when the Swedish government reacted to a severed communication cable linking Sweden and Lithuania, stating that “safeguarding our shared critical infrastructure is vital to our security and the resilience of our societies.”

As one of the largest operators of critical infrastructure in the Nordics, Telenor plays a direct role in safeguarding the connectivity of the region. The company has joined forces with other European telecom operators in signing an Open Letter to the EU, UK, and NATO, pushing for a more coordinated approach to the protection of subsea infrastructure. In that letter, the operators warned that “Europe’s digital lifelines are vulnerable, and their protection requires harmonised approaches across borders”. The letter also called for “joint surveillance and investment in detection and rapid repair technologies, supported through strong public-private partnerships”.

From Telenor the message is clear: no single operator or nation can shoulder this responsibility alone. Public-private partnership is essential to ensure that the protective measures are sustainable, scalable, and grounded in real operational needs. Telenor asserts that regulatory frameworks should be proportionate and risk-based, with firm requirements where they are most critical, while also enabling innovation and collaboration across borders.

Redundancy is another key principle. While subsea cables carry the majority of Nordic data traffic, satellites remain an important back-up. Telenor supports efforts to integrate satellite communication into the broader resilience strategy, as a complement to both subsea and terrestrial connections. A layered model of resilience, combining subsea, with land-based, and satellite connectivity, offers the strongest defence against both accidents and deliberate attacks.

Overall, Telenor views cable security as part of the wider responsibility in which the operators, who manage society’s critical digital backbone, play a critical role. By contributing with expertise, advocating for common standards, and investing in resilience, Telenor intends to be a partner to governments, allies, and industry peers in protecting what lies beneath the surface.

Subsea cables are a hidden foundation of Nordic connectivity. They play a central role in carrying the communications that bind governments, businesses, and citizens, and their protection has become a strategic imperative. The incidents in the Baltic Sea revealed how quickly vulnerabilities can be exploited and how easily societies can be destabilised if this infrastructure fails.

Safeguarding these lifelines requires more than technical upkeep. it calls for sustained investment, cross-border cooperation, and strong public–private partnerships. Resilience will depend on more than one layer of defence. By combining robust protection of subsea infrastructure with secure mobile networks, and by using satellite communication and cloud as complementary backups, the Nordics can strengthen both digital sovereignty and crisis preparedness.

Only through collective action can the Nordics secure the infrastructure that carries our data, sustains our economies, and underpins societal continuity in an increasingly uncertain world.