Undersea infrastructure—including fiber-optic cables, power lines, and oil and gas pipelines—is becoming an increasingly attractive target for hybrid warfare and gray-zone aggression. These critical assets support global connectivity, economic stability, and energy distribution, making their disruption a high-impact strategy for state and non-state actors seeking to destabilize adversaries.

Undersea fiber-optic cables transmit 95% of the world’s internet traffic, enabling financial markets, military communications, and daily online activities. Subsea power lines connect offshore energy sources, such as wind farms, to national grids, while undersea pipelines transport vital oil and gas resources from extraction sites to refineries. A successful attack on these assets could trigger widespread economic turmoil, energy crises, and geopolitical instability.

Hybrid Warfare and the Targeting of Critical Infrastructure

Unlike conventional military conflicts, hybrid warfare seeks to weaken adversaries through non-traditional means, including cyberattacks, disinformation campaigns, and sabotaging critical infrastructure. These tactics serve several strategic objectives:

• Disrupt and Weaken the Enemy: Attacks on key infrastructure can cripple economic and military capabilities.
• Test and Refine Techniques: Sabotage efforts in peacetime can provide valuable intelligence for future operations.
• Psychological Impact: Demonstrating an ability to strike vulnerabilities can rattle opponents and deter countermeasures.

Hybrid warfare operates within the gray zone—pushing the boundaries of aggression while avoiding overt acts of war. Many operations are carried out through civilian proxies or criminal organizations, making attribution difficult and complicating diplomatic or military responses.

Repairing submarine cables and undersea infrastructure.

Recent Incidents and Key Players: Russia and China

The strategic importance of undersea infrastructure has drawn attention from global powers, with Russia and China at the forefront of suspected activities.

Russia’s Undersea Infrastructure Operations

Western intelligence agencies have long suspected Russia of mapping and surveilling undersea assets. Russian spy ships and deep-sea research vessels have been observed near critical infrastructure, raising concerns over potential sabotage operations. The 2022 Nord Stream pipeline explosions, widely believed to be an act of sabotage, highlighted the vulnerability of these assets. Additionally, in the past 15 months, 11 undersea cable disruptions have occurred in the Baltic Sea—though no direct attribution has been made, skepticism remains high.

China’s Expanding Hybrid Warfare Tactics

China has also been linked to undersea infrastructure attacks, particularly around Taiwan. In recent years, Chinese ships—often flagged under other nations—have been suspected of severing multiple fiber-optic cables by dragging anchors in deliberate patterns. Similar tactics were observed in the Baltic region, where two undersea cables, one linking Germany and Finland and another connecting Lithuania and Sweden, were mysteriously cut.

In a further development, a patent published by China’s Lishui University describes a “Dragging-Type Submarine Cable Cutting Device,” a tool engineered to sever communication lines efficiently. Whether China intends to develop this technology or merely signal its capabilities remains unclear, but its release has heightened concerns in the West.

Challenges in Defending Undersea Infrastructure

Protecting assets that stretch thousands of miles through international waters presents a formidable challenge. While Taiwan and NATO have increased patrols near critical undersea infrastructure, the sheer scale of these networks makes it difficult for them to defend against tactics like “accidental” anchor dragging. Moreover, attributing these incidents to a specific nation-state is complex, further complicating diplomatic or military responses.

Given these challenges, defense strategies must extend beyond physical protection. Governments and industries must prioritize:

• Resilience and Redundancy: Developing alternative communication and energy distribution networks to mitigate disruption.
• Rapid Restoration Capabilities: Advancing repair technology to quickly restore damaged infrastructure.
• Enhanced Surveillance and Attribution Methods: Improving tracking and forensic analysis to deter aggressors by increasing the likelihood of exposure and retaliation.

Preparing for the Inevitable

Undersea infrastructure is essential to global connectivity and economic stability, yet it remains a vulnerable and attractive target for hybrid warfare.

As threats escalate, the focus must shift from merely defending these assets to ensuring resilience and rapid recovery in the event of an attack. Governments, private sector stakeholders, and military alliances must act now—before a disruption of global infrastructure forces them to respond in crisis mode.

By: scott.blevins@eiscouncil.org