Addressing the Security of Undersea Infrastructures in the Baltic Sea

Key Takeaways:

●       The Fitburg ship was seized by Finnish authorities on 31 December 2025, after dragging its anchor on the seafloor, damaging an undersea telecoms cable.

●   The incident is the first to take place a year after extensive securitising measures were taken by NATO, the EU, and coastal states to protect the Baltic undersea installations.

●       Baltic maritime affairs impact various business practices, including shipping, communications, and energy, and all could be affected by changes to the geopolitically tense Baltic status quo.

Satellite image of the Baltic Sea and Scandinavia

On 31 December 2025, the Finnish police seized a ship as “part of a joint operation” within the framework of aggravated criminal damage to critical undersea cables. The vessel is suspected of damaging a Baltic undersea telecoms cable across the Gulf of Finland. Repeated cable sabotage incidents had already hit the area since Russia’s invasion of Ukraine in 2022. Eight NATO member states border the Baltic Sea, and all have been on high alert due to the repeated outages of power cables, gas pipelines, and telecoms cables.

The suspected ship had allegedly been dragging its anchor across the seabed and was headed towards Finland’s territorial waters. The cable hit belongs to Elisa, a Finnish telecoms group, and the damage is suspected to be intentional. Another cable running parallel to this one has also experienced an outage on Wednesday, connecting Estonia to Finland. Finnish President Alexander Stubb stated in response to the damage, claiming “Finland is prepared for security challenges of various kinds”.

The ship was later identified as Fitburg, a vessel set for Israel after departing the Russian port of St Petersburg. The undersea cable is considered critical Finnish underwater infrastructure, and the incident comes amid growing fears of Russian sabotage in the Gulf of Finland.

This is not the first time Finnish authorities have had to address damage to power cables. In December 2024, Finnish police boarded the Russia-linked oil tanker Eagle S, which was also suspected of damaging several telecoms cables by dragging its anchor.

NATO’s Baltic Strategy

Since Russia’s war with Ukraine, NATO increased its presence in the Baltic through frigates, naval drones, and aircraft, and has been explicitly interested in looking over cable security in the region. Wednesday’s Fitburg’s cable incident was immediately reported to NATO authorities, with an exchange of information transpiring between Finnish authorities and NATO through the NATO shipping centre at the Allied Maritime Command in Northwood, UK.

The Fitburg incident is also the first such incident since the creation of a NATO task force on defending Baltic cables. NATO set up a Baltic Sentry on 14 January 2025 in an effort “to deter any future attempts by a state or non-state actor to damage critical undersea infrastructure there”. As such, the Sentry allowed for warships and aircraft to be deployed to several NATO nations in the area to deter sabotage incidents.

The largest risk in the Baltic Sea is to the energy and communications infrastructures through the underwater cables and pipelines that cross the sea. NATO, recognising this, has long held regular patrols and joint exercises at the Sea to “enhance readiness”. NATO also holds a Standing Naval Maritime Group 1 (SNMG1), a fleet of warships operating in the North and Baltic seas, standing ready to respond to threats. It increasingly prioritises the Baltic as a strategic area, as it houses “critical infrastructure”. Allies in the region are required to maintain vigilance and enhance situational awareness in the field, as well as to refer to NATO’s Maritime Centre for Security of Critical Undersea Infrastructure.

Security in the Baltic

Existing cables and pipeline structures in the Baltic Sea are essential to the functioning of the states they connect. The advance of artificial intelligence (AI) is also likely to increase the presence of undersea data cables, and states looking to pursue the green transition are likely to increasingly rely on undersea power cables. Such cables can transport data between countries and power from wind farms. Since the EU sanctions on Russia, gas imports from Norway have been increasingly popular, increasing, in turn, the importance of undersea gas pipelines.

The sabotage of undersea cable and pipeline structures by countries, organisations, and non-state actors has been well-known, but largely historically absent due to the United Nations Convention on the Law of the Sea’s (UNCLOS) legal frameworks around undersea installations and the general lack of understanding of the strategic significance of the undersea structures.

There are a series of attempts at securitising the Baltic Sea. The aforementioned NATO-created task force, initiated in October 2024 as the Commander Task Force (CTF) Baltic, was especially significant in recognising the region’s strategic value. The CTF’s official task was “to coordinate naval activities in the region with Germany’s allies and provide them with a current joint maritime situational picture around the clock,” focusing on shadow fleets and threats to undersea structures. The Baltic Sentry is an extension of the CTF Baltic, and is a useful addition for showcasing the Baltic nations’ “solidarity” and “vigilance”. Baltic coastal states also increased their coast guards’ and navies’ patrols. The level of information-sharing between the countries’ authorities is today incomparable to the levels of mid-2023 and before.

The European Union is also active in increasing Baltic Sea security. Part of its achievements includes sanctions on specific shadow vessels and outreach to the countries that flag shadow vessels. Such countries often offer “flags of extreme convenience” and include states like Sierra Leone, the Comoros, Gabon, Barbados, and the Cook Islands. Following the EU’s outreach, some of the states pledged to “de-flag” ships sanctioned by Western governments, affecting shadow vessels. Shadow vessels are not solely responsible for damaging undersea installations, but their lack of transparency around ownership and regulation makes them suspicious during incidents. The EU has additionally implemented its Action Plan on Cable Security, a project to develop information exchange and strengthen joint repair capabilities.

Progress nevertheless remains to be made in the Baltic maritime strategy. More than military operations are threatened, so are civilian maritime activities. Estonia, Latvia, and Lithuania still experience vulnerabilities, lacking the capabilities necessary to deter enemy advancements into their territorial waters, their exclusive economic zones, or essential port infrastructures. Russia remains the main threat to these coastal states. NATO has no jurisdiction over the undersea structures in the case of an incident, and it falls to the responsibility of the coastal states. Security experts hence call for a more comprehensive maritime strategy, by namely incorporating intelligence, surveillance, and reconnaissance capabilities and enhancing communication and command during potential moments of crisis.

Business stakes in the Baltic Sea

Foremost, the Baltic region is increasingly under threat. The Baltic’s growing association with NATO and continued support for Ukraine make it increasingly threatened by Russia. Russia’s grey-zone tactics are expected to increase in kind and can affect public and private players in the region, in terms of energy, communication, and maritime affairs. Critical services to civilian, government, and business activities rely on undersea cables and pipelines to fuel their activities. Incidents of damage, blocking, and outages to these undersea installations in the Baltic Sea have repercussions on the activities of actors reliant on them.

The rising tension in the region is also likely to affect shipping practices. The Baltic Sea, home to 15% of the world’s cargo shipping, is now under growing scrutiny from coastal states and security institutions. CTF, for example, tracks ships through radar and immediately monitors shadow vessels as they approach undersea cables and pipelines. Regulation and transit transparency practices from actors transiting across the sea are expected to increase and become more comprehensive. This could affect businesses’ implementation projects in the region. The call for more public-private information-sharing and collaborative partnerships to better protect private infrastructures is expected to affect business practices in the Baltic region. Such measures, if implemented, could add to the regulatory layers businesses need to pass.

Beyond shipping, Russia holds advanced air combat units and missile systems near the Baltic states, capable of blocking air and maritime access. In the unlikely but possible event of conflict escalation, transit across the region, in any form, could be temporarily halted. The costs, delays, and disruptions to activities requiring travel in the Baltic could extend to businesses. The Baltic Sea is also a key area for states implicated in the green transition. Power cables are often used to relay power from offshore wind farms to Baltic nations. The Baltic offshore energy production market is likely to be affected if the current geopolitical tensions in the region were to escalate, directly impacting the region’s energy production sector and businesses integrated in it.