The Baltic Sea, a vital crossroad for Europe’s digital infrastructure, plays an essential role in the continent’s connectivity. Beneath its surface lies a complex network of undersea cables that are critical for data transmission, internet access, and global communication. These cables, which carry over 95% of the world’s internet traffic, are the lifeblood of the digital economy.
However, rising geopolitical tensions pose increasing threats to this indispensable infrastructure. How can Europe safeguard these vital connections?
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Europe’s Hidden Digital Backbone
The digital age relies on an intricate web of undersea cables stretching across oceans to connect continents and enable global communication. Among these, the undersea cables in the Baltic Sea are particularly critical, serving as a vital artery for Europe’s data traffic. They connect Scandinavian countries, the Baltic states, and Northern Europe to the broader European internet infrastructure and link Europe to Russia and, by extension, the global internet network.
According to TeleGeography’s Submarine Cable Map, the Baltic Sea region is interconnected by numerous submarine cables, among them are:
- Baltic Sea Submarine Cable: Connecting Tallinn, Estonia; Helsinki, Finland; and Stockholm, Sweden
- C-Lion1: Linking Finland and Germany
- BCS East-West Interlink: Connecting Sventoji, Lithuania, to Katthammarsvik, Sweden
- SwePol: Connecting Sweden and Poland
These cables underpin critical services such as cloud computing, multinational business operations, financial market transactions, and online communication. According to industry reports from the National Oceanic and Atmospheric Administration (NOAA), over 95% of global internet traffic relies on undersea cables, highlighting their irreplaceable role in modern life. The economic implications are staggering: a disruption could impact trillions of dollars in daily financial transactions and interrupt essential services for millions of people.
To maintain continuous subsea cable service, Europe has begun deploying advanced surveillance technologies, including underwater drones, seabed sensors, and artificial intelligence systems capable of detecting anomalies. Collaboration with private-sector stakeholders is also underway to improve the resilience of this digital backbone, ensuring Europe remains connected in the face of rising challenges.
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The Growing Threat
Undersea cables are no strangers to risk. Natural disasters, ship anchors, and even marine life pose everyday challenges. Yet, the security concerns surrounding these cables have intensified in recent years. The key threats are now more likely to be deliberate sabotage, cyberattacks, and geopolitical tensions targeting critical infrastructure.
The Baltic Sea, with its proximity to Russia, is particularly vulnerable. Russia’s increasing military activity and its history of using non-traditional warfare tactics, such as hybrid warfare and cyberattacks, poses potential threats to undersea cables. The last few years have raised concerns over possible interference with critical infrastructure, including subsea cables that provide crucial internet connections to the region.
Moreover, the severing of fiber optic cables, such as the C-Lion1 and BCS East-West Interlink, has exposed the vulnerabilities of this infrastructure. The damage to C-Lion1 alone disrupted significant internet connectivity between Finland and Germany, underlining the potential for widespread consequences.
On December 25, 2024, the Estlink 2 power cable and four telecommunications cables between Finland and Estonia were damaged, disrupting services and prompting suspicions of sabotage. Investigations revealed that the oil tanker, Eagle S, carrying Russian oil, may have caused the damage by dragging its anchor across the seabed. Finnish authorities detained the vessel and discovered 32 serious deficiencies during the inspection, preventing it from operating until repairs are made.
In response to these events, NATO has increased its presence in the Baltic Sea to safeguard critical infrastructure. Finland’s Foreign Minister announced that NATO is deploying two ships to monitor undersea assets and deter potential sabotage. Additionally, NATO bolsters surveillance efforts with underwater drones and satellite monitoring to detect anomalous activity that might threaten vital cables.
Furthermore, Finland’s telecom company, Elisa, has repaired two undersea telecommunications cables damaged in the incident. However, fixing the Estlink 2 power cable will take approximately seven months. This disruption has underscored the vulnerability of the region’s power and communication networks, highlighting the urgent need for stronger protective measures.
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Securing the Maritime Digital Frontier
Securing the maritime digital frontier requires a multi-layered approach that combines cutting-edge technology, international cooperation, and proactive security measures.
Europe has ramped up efforts to safeguard undersea cables. This includes deploying sensors along cable routes, utilizing advanced detection systems to monitor unusual activity, and leveraging satellite surveillance to track ships that could threaten the cables. The European Union is making significant investments in monitoring and detecting disturbances to these critical infrastructures, focusing on using unmanned underwater vehicles (UUVs) to inspect and protect cables from potential sabotage.
Additionally, at the beginning of 2025, NATO launched a new mission, Baltic Sentry, to protect undersea cables in the Baltic Sea region. Secretary-General Mark Rutte announced the initiative in Helsinki, emphasizing the strategic importance of undersea cables as they facilitate USD 10 trillion in daily financial transactions.
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Telcos at the Security Forefront
Telecom companies in the Baltic Sea region, such as Telia Company (Telia), Telenor Group (Telenor), Tele2, and Elisa, play a pivotal role in securing undersea cables and digital infrastructure. These companies are maintaining the security and integrity of the subsea networks connecting Europe to the rest of the world.
Telia has implemented Firewall-as-a-Service (FaaS) and a Next-Generation Firewall to curb intrusion attempts and botnets. In addition to technological defenses, Telia ensures robust subsea cable security through its ISO/IEC 27001-certified Information Security Management System (ISMS), incorporating best practices like the NIST Cybersecurity Framework and CIS Critical Security Controls. Key measures include proactive security governance, risk management, and a ‘security-by-design’ approach to integrate security controls into systems and infrastructure from the outset, with annual external audits ensuring continuous improvement and effective threat mitigation.
Telenor’s Security Operations Centre (SOC) provides continuous protection against external threats. Alongside this, Telenor has previously expressed its support for Europe’s NIS2 Directive given its potential in mandating and reshaping the security of vital infrastructure, both below and above the water, with Rolv R. Hauge, Business Continuity Manager at Telenor, emphasizing:
”Robustness and redundancy in infrastructure and systems have become necessary to protect against threats. So has the ability to withstand and recover from a serious incident.”
Tele2 is enhancing the security and resilience of subsea cable infrastructure through its partnership with Equinix Fabric™ by ensuring optimized performance and secure data exchange across networks.
Elisa is strengthening the security and efficiency of its subsea cable and telecom infrastructure through its international software businesses, Elisa IndustrIQ and Elisa Polystar, which provide advanced solutions tailored to manufacturing and telecom customers, ensuring robust performance and innovation.
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Looking Ahead: Strengthening Digital Defenses
As the world becomes more interconnected, securing undersea cables in the Baltic Sea is not just about protecting a few miles of fiber-optic cables; it’s about safeguarding the backbone of Europe’s digital economy. The stakes are high, and the need for robust security measures is growing increasingly urgent as geopolitical tensions rise.
By leveraging advanced technology, strengthening international cooperation, and maintaining a proactive approach to security, Europe is working to ensure its undersea cables remain secure and resilient in the face of evolving threats. In an era where digital infrastructure is as critical as any military asset, protecting these cables is an investment in the future of Europe’s economy, security, and connectivity.
Securing the Baltic Sea’s undersea cables will be an ongoing challenge as Europe continues to fortify its digital infrastructure. It requires a multifaceted approach, combining technological innovation, geopolitical awareness, and international collaboration. Only by securing these critical digital lifelines can Europe ensure its place in an increasingly interconnected and volatile world.