Submarine Cables

The Severed Spine

Submarine Cables, Pipelines, and the Benthic Front

The Fallacy: The Cloud

People say their data is in the cloud. It is not in the cloud. It is in a cable on the ocean floor, thinner than a garden hose, armored in steel, and defended by almost nothing. More than ninety-five percent of intercontinental data travels through submarine fiber-optic cables. Ten trillion dollars in daily financial transactions cross these cables. As of 2025, approximately 570 active systems spanning 1.4 million kilometers connect the global economy, and the primary legal framework protecting them, the Convention for the Protection of Submarine Telegraph Cables, dates to 1884.

The fallacy is that the internet is ethereal. The internet is physical. It is glass fiber encased in polyethylene and steel wire, laid on the seabed by a global fleet of approximately eighty specialized ships, most of them aging toward the end of their service lives. A TeleGeography analysis published in 2025 found that two-thirds of the world’s cable maintenance vessels will reach end of service life within the decade, and that sustaining current repair capacity will require roughly three billion dollars in new investment, covering fifteen replacement ships and five additional vessels. The industry has not funded them. The cloud is a fiber on the seafloor, and the ships that fix it when it breaks are running out of time.

The Center of Gravity: The Cable

Between October 2023 and January 2025, the Baltic Sea experienced at least nine submarine cable cuts and one gas pipeline rupture across four distinct incidents, seven of them in a single three-month window. The SIPRI investigationdocumented the pattern: in every case, the ships involved appear to have deliberately dragged their anchors along the seabed for long distances. The Chinese bulk carrier Newnew Polar Bear damaged the Balticconnector gas pipeline and a data cable between Finland and Estonia in October 2023. A year later, the Chinese-flagged Yi Peng 3 severed two cables connecting the Baltic states to Western Europe. On Christmas Day 2024, the shadow-fleet tanker Eagle S dragged its anchor for nearly ninety kilometers across the Gulf of Finland, cutting the Estlink 2 power cable and four telecommunications cables in a single transit, reducing Finland-Estonia cross-border electricity capacity by sixty-five percent.

NATO responded in January 2025 by launching Baltic Sentry, deploying frigates, maritime patrol aircraft, and naval drones across the region. No confirmed cable severings have occurred in the Baltic since. But NATO’s own commanders acknowledge the limits: the alliance monitors and deters, but coastal states bear primary responsibility for response, and the legal framework under the United Nations Convention on the Law of the Sea does not authorize boarding foreign vessels in exclusive economic zones even when evidence of deliberate cable damage is compelling.

The Baltic is not the only theater. In February 2023, two Chinese vessels severed both cables connecting Taiwan’s Matsu Islands, leaving 13,000 residents with fifty days of degraded internet access. Between 2024 and early 2025, Recorded Future’s Insikt Group identified four incidents involving eight distinct cable damages in the Baltic Sea and five incidents involving five distinct damages around Taiwan, at least five attributed to Russia- or China-linked vessels. In February 2024, the Houthi-struck vessel Rubymar sank in the Red Sea with its anchor deployed, damaging three major cables and disrupting twenty-five percent of internet traffic between Asia and Europe.

Russia and China approach the seabed differently but exploit the same vulnerability. Russia’s doctrine is chaos. Its intelligence ship Yantar, operated by the secretive Main Directorate of Deep-Sea Research, has spent years mapping NATO cable routes from the Norwegian Sea to the Irish Sea to the Mediterranean. In November 2025, Britain’s Defence Secretary stated publicly that Yantar had entered UK waters to map undersea cables, and that the ship’s crew directed lasers at Royal Air Force pilots tracking it. Russia’s shadow fleet of aging, opaquely owned tankers provides the deniable platforms for anchor-dragging operations that remain below the attribution threshold. China’s doctrine is leverage. HMN Technologies, the successor to Huawei Marine Networks, has built or repaired approximately twenty-five percent of the world’s submarine cables according to a Federal Communications Commission report cited by CSIS, giving Beijing structural knowledge of where the cables are, how they are built, and how they are repaired. The United States has intervened in at least six Asia-Pacific cable deals to prevent HMN from winning contracts, but the company’s existing market penetration cannot be reversed.

The same seabed hosts energy pipelines and emerging deep-sea mining claims. The Nord Stream sabotage of September 2022 demonstrated that undersea energy infrastructure is as vulnerable as communications cables. The Iran war, now in its third week as of March 19, 2026, has provided the most devastating proof yet. Iran’s closure of the Strait of Hormuz on March 3 and the simultaneous disruption of the Red Sea corridor by Houthi forces have, for the first time in history, closed both of the world’s critical maritime data chokepoints simultaneously. Seventeen submarine cables pass through the Red Sea. Additional systems run through the Strait of Hormuz serving Iran, Iraq, Kuwait, Bahrain, and Qatar. Alcatel Submarine Networks has issued force majeure notices halting work on the 2Africa Pearls cable extension in the Persian Gulf. Cable repair ships cannot safely reach either passage. The benthic front is not hypothetical. It is on fire.

The Gulf war has exposed precisely the convergence this paper identifies. The 2Africa Pearls cable, designed to carry data traffic for more than three billion people linking Africa, Europe, and Asia, was suspended under force majeure at the same moment that Iranian ballistic missiles struck Qatar’s Ras Laffan Industrial City and drones hit the UAE’s Shah gas field, Fujairah oil zone, and Saudi refinery infrastructure. 

The energy attacks and the digital infrastructure freeze are not separate crises. They share the same geography, the same chokepoints, and the same adversary logic. Amazon, Microsoft, and Google spent years building data centers across the Gulf, betting the region would become the world’s next hub for artificial intelligence. Submarine cables connecting those facilities to users in South Asia, Southeast Asia, and Africa pass through the same straits now closed to commercial traffic. Strategic planning, as one geopolitical analyst noted, revolved almost entirely around energy and financial flows, leaving technology infrastructure vulnerable. The cables, the pipelines, and the data centers are all on the same seabed, in the same war zone, defended by no single authority.

The Convergence Gap

Telecommunications regulators see cable licensing. Navy planners see seabed warfare. Energy security analysts see pipeline vulnerability. Maritime lawyers see the 1884 Convention. Deep-sea mining regulators see resource extraction. The irregular warfare community sees gray zone infrastructure attack. Nobody has converged submarine cable defense, energy pipeline protection, seabed mining security, and undersea infrastructure deterrence into a single benthic warfare doctrine.

The bureaucratic fragmentation is structural. In the United States, the Federal Communications Commission licenses cable landings while the Department of Transportation funds the Cable Security Fleet, a two-ship program operated by SubCom at ten million dollars annually. The Navy monitors the seabed. The Department of Energy tracks pipeline security. The International Seabed Authority governs mining. In Europe, the EU published a cable security action plan in February 2025 while NATO launched Baltic Sentry, but no single authority bridges the two mandates. The 2024-2025 Baltic incidents exposed this gap in real time: Estonia’s power regulator, Finland’s criminal investigators, NATO’s maritime command, and the EU’s policy apparatus all responded to the Eagle S incident through separate channels, on separate timescales, under separate legal authorities. The Eagle S carried a Cook Islands flag, was registered in the United Arab Emirates, was operated by an Indian company, and employed a crew from India and Georgia. Determining who had jurisdiction to act, and under what legal authority, consumed hours that the cable infrastructure did not have.

The Gulf war is now demonstrating the same fragmentation at a global scale. Energy ministries are tracking the Ras Laffan damage and Hormuz closure. Telecommunications regulators are tracking the 2Africa Pearls suspension and cable repair delays. Military planners are tracking Iranian missile trajectories and Houthi maritime operations. No single institution is tracking the convergent effect: that the same conflict has simultaneously closed two submarine cable chokepoints, halted a major cable construction project, destroyed energy infrastructure that shares the seabed with those cables, and frozen data center investments that depend on cable connectivity. The adversary did not plan this convergence. The architecture of the seabed produced it. The absence of a unified defense framework ensured nobody saw it coming as a single system failure.

The adversary faces no such fragmentation. The same shadow-fleet vessel that drags an anchor through a power cable can sever a data cable and a gas pipeline in the same transit. The same intelligence ship that maps cable routes also maps pipeline corridors. The same legal void that prevents boarding a suspect vessel in an exclusive economic zone applies equally to cable cuts and pipeline sabotage. The defenders are organized by infrastructure category. The attackers are organized by geography. This is the gap. Not intelligence. Synthesis.

Naming the Weapon: The Severed Spine

I propose the term the Severed Spine to describe the convergent exploitation of undersea infrastructure vulnerability across communications, energy, and resource domains. The Benthic Front is the contested seabed environment where cables, pipelines, and mining operations coexist under different regulatory frameworks, defended by different bureaucracies, and attacked by the same adversaries using the same platforms.

The Severed Spine operates through three mechanisms. The disruption mechanism: cable and pipeline cuts that degrade communications, financial systems, and energy supply. The intelligence mechanism: cable-laying and repair market penetration that provides structural knowledge of adversary infrastructure. The escalation mechanism: the legal and attribution void that allows seabed operations to remain below the threshold of armed conflict. The median restoration time for a damaged cable is approximately forty days. A coordinated attack on multiple cables in a region with limited redundancy, such as West Africa or the Pacific Islands, could isolate entire nations for months. The European Union Agency for Cybersecurity has warned explicitly that a coordinated attack against multiple subsea cables could have a major impact on global internet connectivity. The Iran war is demonstrating in real time what that impact looks like when two chokepoints close simultaneously.

The Doctrine: Five Pillars of Benthic Sovereignty

First Pillar: Unified Seabed Infrastructure Command. A single authority responsible for the defense of all undersea infrastructure, cables, pipelines, and mining operations, within allied waters. Not three bureaucracies defending three categories separately. One command. One operational picture. One response architecture. NATO’s Baltic Sentry is a step, but it addresses only one sea and only the military dimension. The EU’s cable security action plan, published in February 2025, addresses only telecommunications cables and only the civilian regulatory dimension. Neither covers energy pipelines. Neither covers the Gulf, the Red Sea, or the Taiwan Strait. The model should resemble NATO’s Airborne Warning and Control System: a shared multinational structure with standing authority to monitor, attribute, and coordinate response across the full spectrum of seabed infrastructure. The threat is global and convergent. The defense must be both.

Second Pillar: Repair Fleet Investment. The global fleet of approximately eighty cable ships is aging, overcommitted, and geographically concentrated. TeleGeography’s 2025 analysis projects a three-billion-dollar investment gap. When Vietnam lost seventy-five percent of its data transmission capacity in February 2023 after all five operational cables suffered simultaneous damage, repairs were not fully completed until late November, nine months later, because nearby ships were busy elsewhere. In Africa, where the Recorded Future analysis found the greatest threat lies in regions with limited redundancy and repair capacity, a single repair ship based in Cape Town served the entire continent at the time of major cable outages in March 2024. Repair capacity is deterrence capacity. A determined adversary does not need to cut every cable. It needs to cut cables faster than eighty ships, most of them committed to installation projects, can fix them. Allied defense budgets should fund a minimum doubling of dedicated repair vessels, pre-positioned in strategic regions, with guaranteed response times written into alliance commitments.

Third Pillar: Seabed Surveillance Architecture. Detection must operate at the speed of the threat, not the speed of the investigation after the cable goes dark. NATO’s deployment of uncrewed surface vessels in the Baltic and the UK’s Nordic Warden program, which uses artificial intelligence to assess vessel behavior patterns, represent early steps. Persistent undersea monitoring of critical cable corridors and pipeline routes using acoustic sensors, unmanned underwater vehicles, and satellite tracking of vessels transiting cable zones must become standard infrastructure, not emergency response. Australia, Denmark, and New Zealand have already established cable protection safety zones in their exclusive economic zones, prohibiting anchoring and bottom trawling near cable routes. The model exists. The adoption does not.

Fourth Pillar: Legal Modernization. The 1884 Convention predates powered flight. Article 113 of UNCLOS, which addresses cable damage, does not provide for universal jurisdiction. Criminal jurisdiction applies only if the cable is damaged by a national of the coastal state or a ship flying its flag. When the Yi Peng 3 severed two Baltic cables in Sweden’s exclusive economic zone, investigators required Chinese permission to board a Chinese-flagged vessel. That permission was not forthcoming. The legal framework must be replaced with a modern treaty that criminalizes deliberate interference with undersea infrastructure, establishes binding attribution mechanisms, and authorizes proportional enforcement measures including boarding, impoundment, and arrest. Finland demonstrated in the Eagle S case that firm action within existing law is possible. The law itself must now catch up to the threat.

Fifth Pillar: Market Sovereignty. Four companies, SubCom, Alcatel Submarine Networks, NEC, and HMN Technologies, hold ninety-eight percent of the global market for building and maintaining submarine cables. One of the four is Chinese-owned, placed on the U.S. Entity List in 2021, and has built or repaired a quarter of the world’s cable infrastructure. The conflict of interest is structural and unresolvable. Allied cable-laying and repair capability must eliminate dependency on adversary-linked companies for the construction and maintenance of critical undersea infrastructure. The United States has already blocked HMN from six Asia-Pacific cable deals. The strategy must extend from blocking to building: funding allied manufacturing capacity, training allied crews, and ensuring that the cables NATO depends on are not built by companies whose parent governments are mapping those same cables for sabotage. The email sent this morning, the financial transaction that paid a mortgage, the intelligence that keeps a country safe, all crossed the ocean floor on a glass fiber protected by a treaty written before the lightbulb was common. The spine of the global economy is lying on the seabed. The adversaries who would sever it are already there.

RESONANCE

Atlantic Council. (2025). “How the Baltic Sea Nations Have Tackled Suspicious Cable Cuts.” Atlantic Council Issue Brief. https://www.atlanticcouncil.org/in-depth-research-reports/issue-brief/how-the-baltic-sea-nations-have-tackled-suspicious-cable-cuts/ Summary Elisabeth Braw reports from the NATO task force charged with protecting Baltic undersea infrastructure, documenting the evolution from the Balticconnector incident through Baltic Sentry and the operational constraints of maritime law enforcement.

Capacity Global. (2026). “Iran-US War Puts Subsea Cable Network on a Knife-Edge.” Capacity. https://capacityglobal.com/news/iran-us-war-subsea-cables-threat/ Summary Analysis of the simultaneous closure of the Red Sea and Strait of Hormuz as data chokepoints, the 2Africa Pearls force majeure, and the unprecedented threat to Gulf digital infrastructure.

CSIS. (2025). “Safeguarding Subsea Cables: Protecting Cyber Infrastructure amid Great Power Competition.” Center for Strategic and International Studies. https://www.csis.org/analysis/safeguarding-subsea-cables-protecting-cyber-infrastructure-amid-great-power-competition Summary Comprehensive assessment of the four-firm market structure, HMN Technologies market penetration, the U.S. Cable Security Fleet, and policy recommendations for allied cable resilience.

Global Taiwan Institute. (2025). “China’s Undersea Cable Sabotage and Taiwan’s Digital Vulnerabilities.” Global Taiwan Institute. https://globaltaiwan.org/2025/06/taiwans-digital-vulnerabilities/ Summary Documents the pattern of Chinese vessel cable damage around Taiwan from 2023 through 2025, Taiwan’s fourteen-cable dependency, and the gray zone warfare implications.

Internet Society. (2025). “Enhancing the Resilience of Submarine Internet Infrastructure.” Internet Society Policy Brief. https://www.internetsociety.org/resources/policybriefs/2025/enhancing-the-resilience-of-submarine-internet-infrastructure/ Summary Reports 570 active cables as of 2025 carrying 97-98 percent of intercontinental internet traffic, with approximately 200 disruptions per year, and draws on real-time Pulse platform data to assess resilience.

Lieber Institute, West Point. (2024). “The Baltic Sea Cable-Cuts and Ship Interdiction: The C-Lion1 Incident.” Lieber Institute for Law and Armed Conflict. https://lieber.westpoint.edu/baltic-sea-cable-cuts-ship-interdiction-c-lion1-incident/ Summary Legal analysis of the 1884 Convention, UNCLOS Article 113 jurisdiction gaps, and the customary international law arguments for boarding suspected cable sabotage vessels.

NATO. (2025). “NATO Launches ‘Baltic Sentry’ to Increase Critical Infrastructure Security.” NATO News. https://www.nato.int/en/news-and-events/articles/news/2025/01/14/nato-launches-baltic-sentry-to-increase-critical-infrastructure-security Summary Official announcement of the Baltic Sentry mission deploying frigates, patrol aircraft, and naval drones to protect critical undersea infrastructure.

Recorded Future. (2025). “Submarine Cable Security at Risk Amid Geopolitical Tensions and Limited Repair Capabilities.” Insikt Group. https://www.recordedfuture.com/research/submarine-cables-face-increasing-threatsSummary Identifies 44 publicly reported cable damage events in 2024-2025 across 32 locations, assesses the 80-vessel global fleet, and warns of median 40-day restoration times increasing as repair capacity lags demand.

Rest of World. (2026). “U.S.-Iran War Threatens Gulf AI Infrastructure as Both Data Chokepoints Close.” Rest of World. https://restofworld.org/2026/us-iran-war-gulf-ai-submarine-cables/ Summary Reports the first simultaneous closure of the Red Sea and Strait of Hormuz to commercial traffic, the impact on seventeen submarine cables and Gulf data center infrastructure, and the inability of repair ships to reach either passage.

SIPRI. (2025). “A Legislative Route to Combat Sabotage of Undersea Cables.” Stockholm International Peace Research Institute. https://www.sipri.org/commentary/topical-backgrounder/2025/legislative-route-combat-sabotage-undersea-cables Summary Interview with legal expert Pierre Thévenin on the nine Baltic cable cuts between October 2023 and December 2024, the case for coastal state safety zones, and the Australian-Danish-New Zealand legislative precedent for EEZ cable protection.

Submarine Networks. (2026). “War in the Gulf Severs the World’s Digital Arteries.” Submarine Networks. https://www.submarinenetworks.com/en/nv/insights/war-in-the-gulf-severs-the-world-s-digital-arteries SummaryDocuments the force majeure suspension of the 2Africa Pearls cable project, the cascading impact on SEA-ME-WE 6 and other Gulf cable systems, and the search for overland alternatives.

TeleGeography. (2025). “You’ve Read About Submarine Cable Breaks. Now Read About the Repairs.” TeleGeography. https://resources.telegeography.com/youve-read-a-lot-on-cable-breaks-lately.-have-you-read-about-the-repairsSummary Reports 1.48 million kilometers of cable in service, projects that two-thirds of maintenance vessels will reach end of service life, and estimates a three-billion-dollar investment gap requiring twenty additional ships.

The Diplomat. (2023). “After Chinese Vessels Cut Matsu Internet Cables, Taiwan Seeks to Improve Its Communications Resilience.” The Diplomat. https://thediplomat.com/2023/04/after-chinese-vessels-cut-matsu-internet-cables-taiwan-shows-its-communications-resilience/ Summary Ground-level account of the Matsu Islands fifty-day internet outage following Chinese vessel cable cuts, including the microwave backup system deployment and implications for Taiwan’s fourteen-cable vulnerability.

Invisible Siegecraft: Submarine Cable Vulnerabilities and the Battle for the Deep-Sea Arteries of Global Power

The Invisible Infrastructure of Global Survival

The internet feels weightless. We speak of data living in the cloud, of information flowing through the ether, of wireless connections liberating us from physical constraints. This perception is a dangerous illusion. Beneath the ocean’s surface, stretching across 1.4 million kilometers of seabed, lies the physical nervous system of modern civilization: a network of between 550 and 600 active submarine cable systems that carries 99 percent of all intercontinental data and facilitates over $10 trillion in daily financial transactions.

These cables are not merely important infrastructure. They are the invisible arteries through which the lifeblood of the global economy pulses every microsecond. When a trader in London executes a transaction on the Tokyo exchange, when a surgeon in Berlin guides a robotic procedure in Singapore, when intelligence agencies share time-sensitive information across continents, these communications travel not through satellites but through fiber-optic strands resting on the ocean floor. As the Atlantic Council has documented, three converging trends—authoritarian reshaping of internet topology, centralized network management systems, and explosive growth of cloud computing—have dramatically increased the strategic stakes of this infrastructure.

For decades, the primary threats to this infrastructure were prosaic: fishing trawlers dragging anchors across shallow-water routes, earthquakes severing cables along fault lines, sharks inexplicably drawn to gnaw on repeater housings. These were manageable risks, addressed through redundancy, rapid repair protocols, and careful route planning. But the strategic calculus has fundamentally shifted. What was once a domain of accidental damage has become a theater of deliberate, state-sponsored sabotage conducted under the cover of plausible deniability.

A new form of warfare has emerged: SIEGECRAFT—the systematic strangulation of an adversary’s digital lifelines without firing a shot.

The Seabed as Gray Zone Paradise

The ocean floor presents an almost perfect environment for covert aggression. Consider the convergence of factors that make submarine cables uniquely vulnerable to strategic sabotage.

Physical fragility is the first factor. Modern submarine cables, despite carrying the digital traffic of entire nations, are often unarmored across vast stretches of deep ocean. The logic is economic: armoring adds weight and cost, and the deep seabed historically presented few threats. A cable that costs tens of millions to manufacture and deploy can be severed by a determined adversary with equipment no more sophisticated than a weighted anchor. According to CSIS analysis, between 100 and 150 cable faults occur annually, with 66 percent caused by fishing and shipping activities and 30 percent specifically from anchor dragging.

Geographic concentration compounds this vulnerability. Global data traffic funnels through a handful of chokepoints where bathymetry, geopolitics, and commercial logic converge. The Baltic Sea, with an average depth of only 180 feet and over 4,000 ship transits daily, hosts critical cables linking Northern Europe to the broader internet backbone. The Red Sea corridor carries 18 cable systems representing 25 percent of Asia-Europe traffic through waters increasingly destabilized by regional conflict. The Taiwan Strait, perhaps most consequentially, has witnessed 27 to 30 cable cuts over a five-year period, a frequency that strains credulity as coincidence.

Legal ambiguity provides the final enabling condition. The United Nations Convention on the Law of the Sea, specifically Article 113, criminalizes intentional cable damage but provides virtually no enforcement mechanisms. A vessel operating in international waters or within another nation’s Exclusive Economic Zone cannot be boarded without flag-state permission. A ship flying the flag of a permissive registry can drag an anchor across a critical cable, claim mechanical failure, and face no meaningful consequence. The law, designed for an era of accidental damage, is impotent against adversaries who weaponize plausible deniability.

The Architects of Subsea Disruption

Russia: The Hybrid Warfare Specialist. The Russian approach to submarine cable warfare exemplifies its broader doctrine of hybrid aggression. Moscow maintains a sophisticated capability for seabed operations disguised as oceanographic research. The spy ship Yantar and the newly commissioned General Valery Gerasimov carry deep-diving submersibles, including the nuclear-powered Losharik, capable of operating at depths that place them beyond observation. These vessels have been documented loitering over critical cable junctions in the North Sea and within the Irish Exclusive Economic Zone, actively mapping NATO critical undersea infrastructure.

More insidious is Russia’s shadow fleet: approximately 1,900 vessels by end of Q3 2024 operating under opaque ownership structures, often registered in permissive flag states, characterized by aging hulls and minimal regulatory compliance. These ships, originally assembled to evade oil sanctions, have proven equally useful for infrastructure sabotage. The December 2024 Christmas Day incident demonstrated the model. The Eagle S, a Cook Islands-flagged tanker with documented Russian links, dragged its anchor for approximately 62 miles across the Gulf of Finland, severing the Estlink 2 power cable and four data cables. Finnish Special Forces ultimately boarded the vessel, marking the first enforcement action against suspected cable sabotage under the 1884 Convention since 1959. The damage was done nonetheless—Estlink 2 required over seven months for repair.

China: The Integrated Hegemon. Beijing’s approach differs in sophistication but matches Russia in strategic consequence. China has achieved dominance across the submarine cable value chain through HMN Technologies, formerly Huawei Marine Networks, which controls approximately 25 percent of global cable construction and repair capacity. This market position creates dual concerns. At the hardware level, cables manufactured or maintained by Chinese-linked entities present potential vectors for intelligence collection or embedded vulnerabilities. At the operational level, China’s repair dominance in the Asia-Pacific—through state-linked company SBSS—means that adversaries may find their damaged cables at the back of the repair queue during any regional crisis.

China’s kinetic capabilities have been demonstrated through what might be called salami-slicing tactics against Taiwan’s offshore islands. In February 2023, Chinese sand dredgers and fishing vessels repeatedly severed the two cables connecting the Matsu Islands to Taiwan proper. The 13,000 residents of Matsu experienced a digital blackout lasting 50 days—a proof-of-concept demonstration of SIEGECRAFT that required no missiles, no blockade, and no formal act of war. Research at Lishui University has reportedly produced anchor-like devices specifically engineered for cable cutting at depths beyond typical commercial operations, suggesting Beijing views this capability as worthy of deliberate development.

The pattern has continued into 2024 and 2025. In November 2024, the Chinese vessel Yi Peng 3, departing the Russian port of Ust-Luga, severed both the BCS East-West Interlink and C-Lion1 cables in the Baltic within 24 hours—an incident now under joint investigation by Sweden, Finland, and Lithuania via Eurojust. In January 2025, the Shunxin 39—flying a Cameroon flag with Hong Kong ownership and Chinese crew—damaged the Trans-Pacific Express cable north of Taipei while operating under two separate AIS systems, a signature of vessels seeking to obscure their movements.

Non-State Actors and Proxies. State adversaries need not act directly. The Houthi campaign in the Red Sea during 2024 and 2025 demonstrated how regional proxies can impose global consequences. Cable cuts to the PEACE system and SeaMeWe-4 disrupted Microsoft Azure services and financial platforms across three continents. Whether these cuts reflected deliberate targeting or collateral damage from anchor mines remains debated. The strategic lesson is clear regardless: localized conflict in critical chokepoints radiates outward through the cable network.

Building the Shield: The Defensive Response

Recognition of the threat has catalyzed an unprecedented defensive mobilization across NATO and allied nations.

At the institutional level, NATO has established dedicated coordination cells for undersea infrastructure protection. The Maritime Centre for Security of Critical Undersea Infrastructure, headquartered at Northwood in the United Kingdom, provides operational coordination. The Critical Undersea Infrastructure Coordination Cell in Brussels handles alliance-wide policy integration. These structures aim to transform cable protection from a national afterthought into a collective security priority. In October 2023, NATO Defense Ministers endorsed the Digital Ocean Vision, integrating satellite, surface, and subsea sensors into a unified diagnostic framework.

Operational presence has intensified in parallel. The Baltic Sentry mission, launched January 2025, deploys multinational naval patrols, complemented by the UK-commanded Nordic Warden mission under the Joint Expeditionary Force, to monitor suspicious vessel activity in real time. The objective is deterrence through presence: making it clear that loitering over cable routes will be observed, documented, and potentially intercepted.

Technological innovation offers perhaps the most promising defensive avenue. Distributed Acoustic Sensing, or DAS, converts existing fiber-optic cables into enormous linear microphones capable of detecting approaching vessels, dragging anchors, or submersible activity at considerable distances. Where traditional cable monitoring required dedicated sensor deployments, DAS leverages the cables themselves as surveillance infrastructure. Complementary technologies, including uncrewed surface vessels like the Saildrone fleets tested by Denmark in 2025 and AI-enabled maritime surveillance systems, can identify vessels operating with disabled Automatic Identification System transponders—the signature behavior of ships engaged in covert operations.

The United States has moved to harden its policy framework. The September 2024 New York Principles, announced at the UN General Assembly, established a baseline for allied coordination on cable security. Team Telecom, the interagency body reviewing submarine cable licenses, now applies explicit national security criteria to landing rights decisions. The Congressional Research Service has outlined the protection issues facing Congress, while Deputy National Security Advisor Anne Neuberger’s January 2025 engagement with Nordic-Baltic allies has produced initial frameworks for unified response protocols.

The European Union has issued recommendations on secure and resilient submarine cable infrastructures and launched an EU Action Plan on Cable Security in February 2025 focused on prevention, detection, response, and deterrence. A memorandum of understanding among Baltic NATO allies and the EU now coordinates rapid-response frameworks, though implementation remains uneven.

The Industrial Bottleneck: Repair as Strategic Vulnerability

Detection and deterrence matter little if damaged cables cannot be rapidly restored. Here the West confronts a critical industrial deficit.

The global cable repair fleet numbers approximately 60 vessels, and 65 percent of these ships will reach obsolescence by 2040. New construction has not kept pace with either fleet aging or the expanding cable network. The economics are challenging: cable ships are expensive to build—$50 to $70 million per vessel—expensive to maintain, and generate revenue only when cables break. Commercial operators, understandably, underinvest in capacity that sits idle during normal operations.

Geographic concentration of repair capacity compounds the fleet shortage. In the Asia-Pacific region, SBSS, a Chinese-linked operator, dominates the repair market. During any Taiwan contingency, or indeed any regional tension involving Chinese interests, Western-aligned nations may find their repair needs deprioritized. A cable cut that might normally require two weeks to fix could stretch to months if the available repair ships are otherwise engaged or simply unwilling to operate in contested waters.

The economic asymmetry favors the aggressor. A planned cable repair, conducted in benign conditions with pre-positioned equipment, costs approximately $500,000 to $1 million. An emergency repair in a conflict zone, requiring hazard pay for crews, military escort, and expedited equipment mobilization, can exceed $12 million. An adversary can impose costs at a ratio of more than ten to one simply by keeping repair crews uncertain about when and where the next cut will occur. TeleGeography estimates that $3 billion in investment is needed by late 2025 merely to maintain the status quo—15 replacement ships, 5 additional vessels, and $200 to $400 million in pre-deployed repair kits.

The Emerging Legal Frontier

The detention of the Yi Peng 3 following its suspected involvement in the November 2024 Baltic cable cuts represented the first meaningful enforcement action under the 1884 Convention for the Protection of Submarine Telegraph Cables in over six decades. The precedent, while encouraging, exposed the inadequacy of existing frameworks.

Current international law treats the high seas as a zone of navigational freedom where vessels may transit without interference absent clear evidence of criminal activity. This framework, sensible for an era of legitimate maritime commerce, creates exploitable gaps for adversaries conducting operations designed to avoid attribution. A vessel can exhibit every behavioral signature of cable sabotage—disabled transponder, erratic course over known cable routes, extended loitering—without providing legal grounds for interdiction. As NATO CCDCOE has analyzed, the UNCLOS framework provides inadequate tools for the current threat environment.

Efforts to close these gaps are underway but incomplete. Proposals to redefine permissible interference with vessels displaying suspicious maritime patterns over critical infrastructure have gained traction among Northern European states most directly threatened. The November 2024 establishment of a UN International Advisory Body for Submarine Cable Resilience represents an initial diplomatic response. The challenge lies in balancing enhanced enforcement authority against the broader navigational freedoms that benefit Western commercial and military operations globally. Any precedent that allows boarding of suspected saboteurs also creates precedent that adversaries may invoke against Western vessels.

The Stakes of Inaction

The submarine cable network represents both the central nervous system of global commerce and a catastrophically under-threatened vulnerability. The emergence of SIEGECRAFT—the deliberate, deniable strangulation of digital infrastructure—has occurred faster than institutional responses can adapt. Recorded Future documented 46 incidents in 2024 alone, the highest annual count since 2013. Adversaries have recognized what defenders are only beginning to acknowledge: that massive economic and military harm can be inflicted through actions that fall below the threshold of armed conflict, conducted by deniable actors, in a domain where observation is difficult and enforcement is nearly impossible.

The path forward requires action across multiple domains simultaneously. Investment in sovereign repair capacity must become a strategic priority, not a commercial afterthought. Rapid deployment of distributed acoustic sensing across all Tier-1 cable routes would transform passive infrastructure into active surveillance networks. Legal frameworks must evolve to enable interdiction of vessels displaying clear patterns of hostile activity, even absent smoking-gun evidence of completed crimes. Satellite-based backup systems, including low-earth-orbit constellations like Starlink and OneWeb, should be positioned as emergency failover capabilities for regions most vulnerable to cable isolation.

Most fundamentally, policymakers must abandon the comfortable fiction that submarine cables exist in a separate domain from great power competition. The seabed has become a battlespace. The cables that carry our data, our financial transactions, and our military communications are under active threat from adversaries who have calculated, correctly, that the benefits of sabotage outweigh the minimal costs of plausible deniability.

In the twentieth century, nations fought for control of the oil flowing through pipelines. In the twenty-first, the contest has shifted to the data flowing through cables. SIEGECRAFT has emerged as the defining methodology of this new competition—patient, deniable, and devastating. The nations that recognize this reality, and act upon it, will retain their place in the global order. Those that do not may find themselves, like the residents of Matsu during their 50-day blackout, suddenly and silently severed from the systems upon which modern existence depends.