Europe’s next security test is beneath the sea

Global Watch | 2026-06-19

Europe's next security crisis may not begin with tanks, missiles or aircraft.

It may start with a damaged cable on the seabed, a disabled pipeline, or a cargo ship dragging an anchor across infrastructure that keeps economies online.

That is why the Baltic Sea has become a test case for modern security. Since Russia's full-scale invasion of Ukraine in 2022, the region has seen a series of disruptions affecting power cables, telecommunications links and gas pipelines, echoing wider security concerns.

Some cases remain under investigation. Others have involved vessels tied to opaque ownership structures, sanctions evasion or routes connected to Russian ports.

The lesson is not that every fault is sabotage. Maritime accidents happen.

The sharper point is that Europe now has to defend infrastructure built for efficiency, not confrontation.

Sabotage goes underwater

Submarine cables carry nearly all intercontinental internet traffic. They also support financial transactions, government communications, energy trading, cloud services and military coordination, a vulnerability already visible in wider undersea infrastructure debates.

That makes them easy to overlook in peacetime and difficult to replace in a crisis.

The European Commission has acknowledged that submarine cables connecting Europe have suffered multiple incidents in recent years. Its 2025 cable security action plan focuses on prevention, detection, response, recovery and deterrence.

That shift shows that Brussels now treats the seabed as part of Europe's strategic exposure.

The Baltic Sea shows why that matters.

Finnish police said June 5 that four people were suspected in an investigation into damage to two subsea telecommunications cables in the Baltic Sea. The Fitburg cargo ship was seized Dec. 31 while traveling from Russia to Israel on suspicion of damaging cables running across the Gulf of Finland to Estonia.

The case has been referred to prosecutors, who will decide whether to file charges.

The case followed earlier incidents involving power cables, telecommunications links and gas pipelines. It also came as NATO increased its presence in the Baltic Sea with frigates, aircraft and naval drones.

This is where the gray zone becomes difficult to manage.

A missile strike is visible. A damaged cable is ambiguous.

It may be sabotage, poor seamanship, equipment failure or an incident designed to look accidental.

That uncertainty gives hostile actors room to test reaction times while reducing the risk of direct military escalation.

Analysts have pointed to Russia's "shadow fleet" as one source of concern. RAND has described these vessels as operating through complex ownership structures, flags of convenience, weak insurance arrangements and tracking gaps.

Their primary role is to sustain Russian oil exports under sanctions pressure. But the same opacity can also complicate investigations into maritime incidents.

That does not prove state direction in every case.

It does, however, create an environment in which deniable disruption is harder to detect, attribute and deter.

Deterrence moves offshore

NATO's response has been practical rather than symbolic.

In January 2025, the alliance launched Baltic Sentry to strengthen protection of critical infrastructure in the Baltic Sea. Secretary General Mark Rutte said the mission would enhance NATO's military presence and improve the ability of allies to respond to destabilizing acts.

The mission includes frigates, maritime patrol aircraft and naval drones. It also brings national surveillance assets and industry into a wider network designed to protect undersea infrastructure and improve resilience.

That matters because no alliance can watch every cable, pipeline and landing point all the time.

The realistic goal is not perfect protection. It is better awareness, faster response and higher costs for actors that use commercial shipping or legal ambiguity as cover.

Europe's challenge is also legal.

Much of this infrastructure lies in exclusive economic zones or international waters, where authorities may have limited power to board or detain a vessel without clear evidence or flag-state cooperation.

Carnegie analysts have noted that European states must prepare for cases in which the legal mandate is less concrete than in recent inspections.

That is why deterrence now depends on a mix of tools: maritime surveillance, sanctions enforcement, insurance scrutiny, port-state controls, forensic investigation and closer public-private coordination.

Military patrols are only one part of the answer.

The United States and allied states have a clear interest in this response because transatlantic data flows, defense communications and financial systems depend on the same physical networks.

But the issue is broader than alliance politics.

It affects Europe's energy security, the private companies that own much of the infrastructure, and smaller states that may have fewer redundant routes if a cable is cut.

The strategic inference is clear.

Undersea infrastructure has become a pressure point because it is vital, exposed and difficult to defend without escalation. A hostile actor does not need to dominate the Baltic Sea to create uncertainty there.

It only needs to make every outage politically suspicious and every repair a security question.

The answer is not panic. It is resilience.

More patrols can reduce risk. Better cable mapping, faster repair capacity, stronger insurance rules and coordinated sanctions can reduce vulnerability.

Clearer legal pathways can also make enforcement more credible.

The seabed is no longer a technical space separate from geopolitics. It is part of Europe's security perimeter.

The countries that adapt fastest will be better positioned to keep their economies connected, their energy systems stable and potential adversaries uncertain about the cost of disruption.