Chokepoints of the Digital Ocean: Securing Subsea Cables

09/05/25

By The Security Nexus
When most people think of the internet, they think of the cloud. But the cloud has roots—and those roots run along the ocean floor. Nearly every byte of information crossing oceans today moves through over 1.4 million kilometers of fiber optic cables hidden beneath the sea. These are the arteries of the global internet, carrying financial transactions, streaming data, intelligence feeds, and mission-critical military communications.
Yet these lifelines are largely invisible—and deeply vulnerable.

The Triple Invisibility of Infrastructure
Subsea cables are subject to what Bueger and Liebetrau (2021) call “triple invisibility.” First, they are infrastructure—often taken for granted until they fail. Second, they are literally buried—either beneath the seabed or embedded in coastal facilities. Third, they lie beneath international waters, where “sea blindness” dominates policy discourse. This invisibility has led to chronic underinvestment in protection, surveillance, and resilience.
Despite transmitting 99% of transoceanic digital communication, policymakers and the public often overlook these systems. Yet, as the podcast explores, these cables are critical—not just for consumer internet use, but for the integrity of global finance, cloud computing, and defense command-and-control networks.

Natural Hazards and Climate Threat Multipliers
As the episode outlines, natural disasters are a major and rising threat. The 2022 Hunga Tonga–Hunga Haʻapai eruption severed Tonga’s only international cable, cutting the country off for weeks. Clare et al. (2023) find that river floods, submarine landslides, and deep-ocean currents—amplified by climate change—pose increasing risk to cables worldwide. Even storm surges and rising sea levels threaten shoreline landing stations, particularly in low-lying nations.
These aren’t abstract dangers. A 2020 Congo River turbidity current traveled over 1,000 kilometers underwater, snapping multiple cables that connected West and South Africa. By 2030, thousands of kilometers of U.S. coastal infrastructure could be submerged due to sea-level rise (Clare et al. 2023).

Accidents, Anchors, and Human Error
The most frequent cable faults, however, come from us—humans. Ship anchors, bottom trawling, and dredging cause over 70% of cable breaks annually. Though typically unintentional, such incidents can lead to cascading outages. Even a minor anchor drag in a high-traffic area can disrupt internet connectivity for millions.
Then there are “accidental” incidents with unclear intent. In Vietnam, confusion over government plans led fishermen to unintentionally destroy much of the nation’s fiber-optic infrastructure. Elsewhere, acts of miscommunication or misinterpretation have triggered severe disruptions.

Espionage, Sabotage, and Hybrid Warfare
Malicious threats are growing. From the 2013 sabotage of Egypt’s SMW-4 cable to suspected Chinese involvement in Taiwan cable cuts in 2023, deliberate tampering is increasingly likely. The U.S. tapped Soviet cables during Operation Ivy Bells; today’s adversaries may use similar or more advanced techniques.
Publicly accessible maps reveal the physical routes of many cables, making them soft targets. Russian submarines observed near cable chokepoints have sparked fears of hybrid warfare campaigns. As Schaub et al. (2017) note, cables would be “prime targets” in any state-based conflict below the threshold of open war.
Metadata and encrypted traffic can also be harvested now for future decryption—especially if quantum computing becomes viable. This is not just about disruption, but long-term strategic advantage through interception.

Governance Gaps and the Digital Sovereignty Struggle
Subsea cables are transnational but mostly privately owned. As the transcript notes, over 59% of bandwidth is now controlled by firms like Google, Meta, and Huawei. This raises profound governance questions.
Bueger and Liebetrau (2021) identify three dominant narratives: cables as (1) security targets, (2) technical management challenges, and (3) regulatory puzzles. While UNCLOS (Article 21) gives coastal states limited control within territorial waters, enforcement and oversight remain fragmented. Many nations have failed to implement their legal obligations to protect cables.
This vacuum has become a geopolitical battleground. China’s Digital Silk Road includes global cable construction. The U.S. now excludes Chinese suppliers from key cable projects under initiatives like Clean Network. Meanwhile, states like Egypt and New Zealand have begun asserting stronger sovereign control through duplication, cable protection zones, and ownership stakes.

Deterrence, Detection, and Redundancy
So what can be done? As outlined in the podcast, the answer is layered:

Physical Protection: Burial and armoring—especially near shorelines or chokepoints—is critical. But it’s cost-prohibitive for the entire network.
Persistent Surveillance: AUVs and UUVs are game-changers. Using magnetic sensors, sonar, turbidity sensors, and ADCPs, they can detect disturbances, anchor drags, or suspicious underwater activity. Systems like those studied by Yu et al. (2018) and Shen et al. (2024) show high promise in hostile environments.
Redundancy: Smart routing and spare capacity are key. Egypt, for example, duplicates Mediterranean cables. Companies are also building alternative paths to avoid known chokepoints like the Suez Canal.
Encryption and Data Hygiene: Pushing end-to-end encryption and adopting quantum-safe protocols is critical to mitigating espionage threats.
Collective Governance: NATO, the Quad, and EU states must elevate cable protection to a strategic priority. Initiatives like the Quad’s 2023 Cable Connectivity and Resilience framework are steps in the right direction—but coordination remains ad hoc.

Conclusion: The Depths of Interdependence
As the podcast closes, it leaves us with a stark thought: the deeper we go, the more fragile our digital civilization appears. Cables are not just technical infrastructure—they are strategic assets. They reflect our interdependence and our vulnerabilities, and securing them will require the kind of international collaboration rarely seen outside of war.
It’s time we brought these invisible lifelines into the light—and treated them accordingly.
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Sources Bueger, Christian, and Tobias Liebetrau. 2021. "Protecting Hidden Infrastructure: The Security Politics of the Global Submarine Data Cable Network." Contemporary Security Policy. https://doi.org/10.1080/13523260.2021.1907129. Clare, M. A., et al. 2023. "Climate Change Hotspots and Implications for the Global Subsea Telecommunications Network." Earth-Science Reviews 237. https://doi.org/10.1016/j.earscirev.2022.104296. Yu, Caoyang, et al. 2018. "Robust Magnetic Tracking of Subsea Cable by AUV in the Presence of Sensor Noise and Ocean Currents." IEEE Journal of Oceanic Engineering 43 (2): 311–322. https://doi.org/10.1109/JOE.2017.2768105. Schaub, Gary, Jr., et al. 2017. "Hybrid Warfare and the Gray Zone Threat to Undersea Cables." Center for Military Studies. https://cms.polsci.ku.dk. Shen, Xiaoming, et al. 2024. "Adaptive Neural Control of Flight-Style AUV for Subsea Cable Tracking under Electromagnetic Localization Guidance." Sensors. https://doi.org/10.3390/s20030737. Matley, Zoe. 2019. "International Legal Frameworks for Submarine Cable Protection: An Australian Perspective." Australian Journal of Maritime and Ocean Affairs 11 (3): 173–189. Sunak, Rishi. 2017. "Undersea Cables: Indispensable, Insecure." Policy Exchange. https://policyexchange.org.uk/publication/undersea-cables-indispensable-insecure/.