Finland Identifies Four Suspects in Undersea Cable Damage

Finland’s National Bureau of Investigation (NBI) has announced the conclusion of its criminal investigation into the damage of two undersea communication cables in the Gulf of Finland on December 31, 2025. According to reports from Tom’s Hardware, four suspects have been identified and referred to prosecutors to determine whether charges should be filed.

Investigation Overview

According to the NBI’s announcement, the cargo ship Fitburg was navigating the Gulf of Finland when it dragged its anchor across the seabed for several kilometers, severing cables owned by Finnish telecom operators Elisa and Arelion Finland. The 132-meter-long Fitburg, registered in Saint Vincent and the Grenadines, was en route from St. Petersburg to the port of Haifa, Israel.

Following the incident, the vessel was seized on New Year’s Eve and detained until mid-January. A joint Finnish-Estonian investigation team examined the ship, the damage site, and the devices of the crew. The 14 crew members were nationals of Russia, Georgia, Azerbaijan, and Kazakhstan.

Mechanism of Undersea Cable Damage

The cable damage occurred within Estonia’s Exclusive Economic Zone (EEZ). Finland has investigated the incident under three charges: “aggravated criminal damage,” “attempted aggravated criminal damage,” and “communications disruption.”

Interestingly, Finnish Customs separately confirmed that steel cargo on the vessel was subject to sanctions against Russia. However, because the cargo entered Finnish territorial waters only after authorities ordered the ship to move, no criminal charges were filed in that matter.

At the time, Elisa stated that it was able to maintain service by rerouting traffic. This aligns with an analysis by Cloudflare following a previous Baltic Sea cable damage incident, which noted that “due to the high density of redundant routes in the region, the observable impact on connectivity was limited.”

Russia’s “Shadow Fleet” and Geopolitical Context

This incident is strikingly similar to the Eagle S incident that occurred in August 2024. At that time, the Cook Islands-flagged oil tanker Eagle S dragged its anchor across the seabed for approximately 56 miles (about 90 kilometers), damaging five cables. Repair costs for two Finnish companies reached approximately $70 million (about ¥10.5 billion).

Eagle S is widely regarded as part of Russia’s “shadow fleet”—a group of oil tankers operating under foreign flags to evade sanctions. Finland has charged three individuals (crew members of Eagle S) with aggravated sabotage and aggravated communications disruption.

NATO’s Response and Technical Limitations

In response to the Fitburg incident, Finland established a dedicated maritime surveillance center for the Baltic Sea in January 2025. NATO has launched a larger operation called “Baltic Sentry,” deploying frigates, maritime patrol aircraft, more than 20 unmanned surface vessels, and software to detect suspicious ship movements.

However, these measures have fundamental limitations. As Tom’s Hardware’s article points out, there is no means to physically prevent the act of dragging an anchor. All that is needed is a vessel willing to drop its anchor over a cable route. Finland has confirmed at least seven major incidents of undersea infrastructure damage by ships since 2023.

Effectiveness of Cable Redundancy

A notable aspect of this incident is that the actual impact on data traffic was limited. According to Cloudflare’s analysis, the Baltic Sea region has a dense concentration of multiple undersea cable routes; when one cable is cut, traffic is automatically rerouted via other paths. This design philosophy is a core principle of the internet.

In other words, physical cable disruption manifests not as a “service outage” but as “increased costs and worsened latency.” For corporate users, the long-term risk of recovery costs being passed on to service fees may be more significant than the direct impact of the disruption.

Editorial Opinion

Short-term impact: The conclusion of this investigation and referral to prosecutors demonstrates Finland’s serious commitment to protecting undersea infrastructure. This is the second such referral following the Eagle S incident in 2024, and Finland’s surveillance capabilities will likely be further strengthened over the next three to six months. The Baltic Sentry operation will increase NATO’s presence, but it does not provide a fundamental countermeasure against physical “anchor dragging.” Companies should reconfirm their own route redundancy and, especially if relying on traffic through the Baltic, prioritize securing alternative routes.

Long-term perspective: Over a one-to-three-year span, we can expect an increase in insurance premiums for undersea cables and stricter risk assessments during route selection for new construction. Additionally, network designs that account for “physical sabotage” may become a new standard. The traditional practice of concentrating multiple undersea cables in the same geographic area will likely come under scrutiny. Furthermore, hybrid configurations combining satellite communications with undersea cables could become the standard architecture for large enterprises and government agencies.

Editor’s question: Who should bear responsibility for the physical security of undersea cables? Surveillance by military organizations like NATO has its limits, and asking private operators to self-defend is not realistic. While cases like Finland’s, where national investigative authorities intervene, may increase, their effectiveness as a deterrent is questionable. We encourage readers to check which undersea cables their own data traverses and how much redundancy exists. You may be surprised to find a significant reliance on single points of failure.

References

• Tom’s Hardware: Four suspects identified in Finland undersea cable damage investigation — Published June 8, 2026
• Official announcement from Finland’s National Bureau of Investigation (NBI) (if applicable)