Irregular Warfare on the Sea Floor and the Case for National Resilience

The global seabed has emerged as a critical domain of strategic competition, where fiber-optic cables—the unseen arteries of modern civilization—now represent both vital infrastructure and strategic vulnerability. Since the laying of the first telegraph cables in the mid-nineteenth century, undersea communication networks have transformed from purely commercial endeavors into critical components of national security architecture. Today, with over 95% of international data traversing these submerged pathways, the security of undersea cables has become inseparable from global economic stability, information dominance, and strategic resilience. This reality demands a comprehensive approach to national resilience that integrates military capacity, civil preparedness, technological adaptability, and international cooperation. By developing multilayered defensive strategies, including enhanced monitoring systems, international security cooperation, physical cable hardening, and credible diplomatic pressure, the United States and its allies can significantly reduce both the likelihood and potential impact of undersea infrastructure attacks in an increasingly contested global environment. 

Strategically, the significance of undersea communication infrastructure has evolved dramatically since the laying of the first telegraph cables in the mid-nineteenth century. Today, undersea fiber-optic cables represent a critical vulnerability in the global security architecture, one that aligns ominously with the warning in the 1986 Joint Low Intensity Conflict Report: “Our adversaries are confronting us with political violence short of conventional war to achieve their goals. If most forecasts are correct, this is precisely the form of conflict that will confront us in the years ahead.” This assessment has proven prophetic, as the character of warfare has shown itself, again, to be Clausewitz’s chameleon in its newest adaptation—a multi-domain, multi-modal conflict landscape where strategic effects can be generated on the seafloor with something as seemingly innocuous as a ship’s anchor. 

The military significance of such cables quickly became clear during the Spanish-American War of 1898, when one of America’s first operational activities involved cutting Spanish telegraph cables to isolate and disrupt communications. During World War I, British naval forces systematically targeted German undersea cables, forcing communication through channels that could be more easily monitored. The Cold War subsequently saw the rise of sophisticated submarine operations targeting undersea infrastructure for intelligence-gathering purposes rather than disruption. The transition from copper telegraph cables to fiber-optic technology in the 1980s and 1990s fundamentally transformed both the capacity and vulnerability profile of undersea infrastructure. As undersea cables have grown more vital to the globalized, they have simultaneously become more vulnerable to sophisticated attacks that can achieve strategic effects without triggering military responses. 

The persistent deliberate targeting of undersea cable infrastructure represents a significant evolution in the methods used for conducting undersea warfare, triggering the need for proactive multifaceted approaches to counter such methods rooted in national resilience. By establishing a comprehensive resilience framework—using enhanced monitoring and surveillance, international cooperation, cable hardening techniques, and diplomatic pressure—the United States and its allies can significantly enhance the security of undersea cable infrastructure and effectively mitigate the domestic and global security, economic, and sociopolitical implications of disruptions in critical data dataflows. Such measures are essential to ensure the continued flow of vital communications and safeguard against both state and state-sponsored actors seeking to achieve asymmetric advantages. 

Nearly all international data flows through undersea fiber-optic cables, making them vital for global communication, finance, and commerce; they are the backbone of global communications. In more granular detail, undersea cables support most of the international data traffic, including emails, webpages, and video calls, making them essential for global connectivity. In addition, these cables support everything from financial transactions to national security communications; essentially, most of the world’s internet relies on these cables to function effectively. In other words, when compared to other communications architecture like broadcast, multicast, or cloud communications, no other system has the same data transmission speed or bandwidth as undersea cables. 

Undersea Cable Attacks: A Mode of Irregular Warfare 

Attacks on undersea cables represent an increasingly likely vector of attack by state and state-sponsored actors in strategic competition and conflict. These attacks align with the characteristics of irregular warfare, as they employ asymmetric methods to achieve political objectives below the threshold of conventional military conflict. Given the strategic importance of cable infrastructure, it would be prudent to consider that potential adversaries may be developing capabilities to target undersea cables as part of broader operations intended to disrupt regional stability. In the global competitive strategic environment, major revisionist powers like Russia and China seek to disrupt or destroy global undersea cable infrastructure to generate their own competitive advantage and erode or neutralize U.S. and allied capabilities. 

Beyond the immediate global connectivity effects of a deliberate attack, cascading secondary and tertiary economic effects could significantly disrupt the global economic ecosystem, which relies heavily on continuous communication to function efficiently. For example, the Apollo North cable system, part of the wider Apollo system, is arguably the most important undersea link between the US and the UK, designed to carry large amounts of data traffic. While there is redundancy in the system, it stands to reason that all such cables could become targets during a conflict.  If this cable architecture were disrupted temporarily or destroyed, the financial consequences could substantially impact international money markets while the initial shock was absorbed and may have longer term consequences as investors sought to protect assets. More troubling is that in a conflict scenario, it could then take weeks or months to get a cable-laying ship in place to repair the splice in the fiber, re-lay the cable, test it, and put it back in service. 

Given the critical importance of undersea cables, it is no surprise that such cables have been identified as key targets for sabotage and destruction. In the case of Apollo North, infrastructure is deep underwater, on average at about 4,000 meters below the surface, which makes it a relatively easy target for an aggressor to damage with sophisticated naval vessels, underwater drones, or commercial shipping traffic, all of which can be unattributable or otherwise difficult to prove malicious intent. Regardless of attribution, the ability to disrupt internet access and other vital services offers key competitive advantages to an aggressor seeking to manipulate the strategic environment. Disrupting data flows could provide an aggressor with a potential strategic advantage in the early phases of a conflict, complicating the US and allied ability to coordinate certain aspects of their response, though dedicated military communications systems maintain significant redundancy. The same logic could apply to economic warfare, where an aggressor trying to generate economic advantage may disrupt or destroy cable architecture to force another nation to make economic concessions. Plausible deniability to generate advantage or create tension without armed conflict is an asset, especially in the murky liminal space between war, competition, and peace.  

Such malign operations are particularly concerning in regions with high geopolitical tension, such as the Baltic and South China Sea, which are home to U.S. allies and partners, major shipping lanes and port infrastructure, and global adversaries. In regions like these, where important cables are densely concentrated and more accessible to potential adversaries, cable infrastructure is more vulnerable because of proximity, capability, and opportunity. Choke points in regions with multiple states, like the Baltic or South China Sea, or in coastal areas with major port infrastructure, like Los Angeles or Rotterdam, in which the maritime domain is constantly busy, are easy targets for targeting, disruption, or destructive operations. 

 But cable infrastructure is also globally dispersed and often far from shore, out of sight and out of mind. Distance, therefore, creates additional operational challenges in terms of undersea cable defense and definitively attributing acts of sabotage to an aggressor. In other words, as cables move away from densely populated and thus more closely monitored areas, the opportunity to attack cable infrastructure unnoticed grows exponentially. The Trans-Pacific Cable (TPC), for example, is a series of cable networks that link Japan, Guam, Hawaii, and the mainland United States. The vastness of the Pacific Ocean offers ample space to hide sabotage far from shore and obfuscate who or what was used to execute the operation, significantly complicating attribution efforts and extending timelines for cable repair operations. 

Though the immediate economic and communications problems resulting from data disruption are acute on their own, there is the additional potential for social unrest, political instability, and violence due to limited access to information and, by extension, fear in a world accustomed to instantaneous and uninterrupted global communications. This fear will compound as data disruption prevents individuals from accessing bank accounts, removing the ability to purchase daily necessities—food, water, fuel, and medicine—and complete routine housing, debt, and service payments. Businesses, unable to track sales and shipments, will be unable to maintain stock or temporarily halt operations, quickly creating scarcity and unrest as citizens look to secure access for their families. While loss of access to information is highly disruptive, prolonged inability to access electronic payment systems could create significant challenges for purchasing essentials like food and medicine, particularly for vulnerable populations without alternative payment methods. The systemic disruption caused by disruption of data flows further obfuscates the precise target sector or intended outcome of a cable attack, making this emerging threat methodology one of the most insidious and effective. 

A complicating facet of undersea cable attacks is that the data transmitted by each cable is multinational and owned by individual citizens, private companies, and governments. The complexity and fragmented nature of data ownership offers the aggressor the ability to hide a specific target in the white noise of modern transmission methodologies, further complicating definitive attribution efforts. For example, an attack intended to disrupt government communications will likely also disrupt private communications and economic connectivity. Thus, an attacker can layer effects and amplify the damage and confusion created by an attack. When used as a component part of a broader strategy to destabilize a targeted country without triggering a full-scale conventional or irregular military conflict, undersea cable sabotage or destruction operations offers an attacker an attractive option for a fait accompli without necessarily triggering a casus belli.  

When relatively inexpensive unattributable operations can create major disruptions to internet access and communication networks, affecting everything from financial transactions to data flows, reappraisal of several fundamental assumptions about competitive advantage, information dominance, and cognitive maneuver becomes necessary.  Reappraisal of these assumptions, like the unconstrained flow of information of all kinds, is rendered more complex because an attack on undersea cables could impair a nation’s emergency response capabilities, potentially degrading decision-making and communication effectiveness during a critical period. The United States and its partners and allies should develop the capacity to effectively manage and mitigate the potential threat of widespread information and communications disruptions and the economic challenges that might follow in order to minimize the immediate damage and secondary effects of a deliberate undersea cable attack. Facilitating systemic resilience across critical sectors at the national, international, and global levels can help to insulate and defend against the shocks produced by undersea cable disruptions and increase the effectiveness of any response strategies. 

Redundancy, System Resilience, Threat Mitigation 

Clearly, vulnerabilities in undersea cables exist and are being exploited for malign purposes by revisionist powers. A recent example of such exploitation happened in the waters around Taiwan. The Taiwanese are investigating a case of undersea cable sabotage and suspect China is responsible for it. The suspected sabotage occurred near Taiwan’s northeast coast and disrupted internet connectivity. The immediate effects sparked concerns about China’s potential use of cable sabotage tactics to disrupt Taiwanese social cohesion and economics. But existing system redundancy can help to mitigate the effects a deliberate attack would have on a target nation or population. To be sure, undersea cable infrastructure is designed with a significant level of redundancy to ensure resilience and minimize disruptions if a cable is damaged or severed, allowing data traffic to be rerouted through alternative paths. Data routing, for example, is a cost-effective way to reroute information flows if a cable is damaged. Data traffic can be quickly rerouted to other available cables, minimizing any noticeable impact on network connectivity.  There is also the value of having multiple cables to provide safety in numbers. The Apollo North infrastructure is a good example of a redundant system that integrates these two approaches. But in the case of a deliberate attack on cables, existing redundancy is likely insufficient to insulate a nation from the more dramatic effects such an attack would have. 

The concept of national resilience, frequently invoked in defense and security discourse, requires a precise definition when applied to critical infrastructure protection. According to the Resistance Operating Concept, resilience constitutes “the will and ability of a partner nation’s government-military-people to withstand external pressure to their national sovereignty, unity, and resolve.” Building on this definition and ongoing work in resilience studies, national resilience for undersea cable protection must integrate military capacity, civil and individual preparedness, and technological adaptability to withstand and recover from strategic shock. For resilience to effectively protect undersea cable infrastructure, and any other infrastructure or society for that matter, it must incorporate these critical dimensions: 

First, resilience must be inherent or embedded within existing national institutions and society rather than looked for externally. Military, government, and civilian organizations must develop organic capabilities to absorb system shocks and respond without the paralysis caused by information disruption. Second, resilience must be intentionally designed and systematically incorporated into national security architecture. This dimension requires deliberately engineered systems that enhance baseline strength, flexibility, and redundancy. Beyond traditional defense planning, this includes legislative frameworks that mandate cable protection standards, multi-level coordinating mechanisms between public and private stakeholders, and community-level preparation for communication disruptions. Finally, resilience must include additive components—external injections that bolster internal capacities. International cooperation, allied support mechanisms, and coordinated multinational responses represent crucial external elements that augment national resilience. With that said, countering undersea cable operations in the context of the resilience framework laid out above requires international investment and development in four key areas. 

A Real-World Example of Cable Sabotage and the International Response 

A high-profile incident in the Baltic Sea last November prompted European investigators to scrutinize a Chinese commercial vessel suspected of intentionally dragging its anchor for more than 100 miles, severing two undersea cables in the Baltic Sea. The Danish navy boarded the suspected Chinese bulk carrier, which was traveling from St. Petersburg in the Baltic during the time frame of two cable breaks on November 17-18. Its Automatic Identification System record indicates unusual course and speed changes at suspicious locations, leading to increased scrutiny from European authorities. After inspection, the anchor of the Yi Peng 3 appeared damaged, which maritime experts suggest indicates it became stuck or was dragged on the seabed. Governments around the Baltic are working on the assumption that the cable damage was intentional, with the German Defense Minister calling it a hybrid action and suspecting sabotage. Whether or not the incident was deliberate remains speculative. Regardless, some key first steps the international community can take immediately are 

Increased Monitoring and Surveillance: 

Several advanced monitoring systems have demonstrated effectiveness for undersea infrastructure protection. The evolution of these technologies represents a significant advance from the rudimentary patrol vessels used to protect telegraph cables in the early twentieth century. Contemporary systems include sophisticated diver detection systems (DDS), autonomous undersea vehicles (AUVs), and integrated sensor networks capable of detecting threats at considerably greater distances and with higher reliability than historical methods. The integration of DDS technology with “smart cables” represents a particularly promising development. When combined with AUVs equipped with acoustic, optical, and magnetic sensors, these systems create a comprehensive sensor network that significantly complicates covert access to undersea cables. 

Still, identifying the precise location of a disruptive or destructive attack poses operational problems that will need to be overcome until comprehensive monitoring is available. A major step toward comprehensive monitoring and notification of disruption is a system developed that listens for acoustic signatures of disruption. Acoustic warning systems like this can detect a diver touching or otherwise manipulating an undersea cable or a ship dragging its anchor. Systems like this are far from perfect, and the technology remains in its infancy, but acoustic detection is an example of a novel technological solution deployed to defend against an emerging attack vector. 

International Cooperation: 

In the international space, implementing cable security zones, deploying cable security patrol ships, and codifying security training for the personnel who maintain and monitor undersea cables add additional layers of resilience. Designated undersea protected zones around cable routes and robust measures to restrict vessel traffic and other activities that could pose a threat around cables can only complicate aggressor operations.  Baltic Sentry could be the model for international cooperation and the defense of undersea cables. Baltic Sentry amplifies NATO’s presence in the region by deploying ships, drones, and aircraft to monitor the Baltic Sea. Artificial intelligence also plays a key role in Baltic Sentry because it enables the alliance to monitor suspicious activities and detect uncrewed underwater vehicles (UUVs). Perhaps most importantly for its utility as a global model, Baltic Sentry enables the alliance to sanction vessels by targeting crews, owners, and intermediaries that may be acting on behalf of a malign actor. Critically, the initiative also diversifies cable routes to allow data and power flow even if a cable is cut or fails. 

Cable Hardening: 

Undersea cable hardening is deliberate cable routing to avoid high-traffic areas, cable armoring to defend against deliberate physical sabotage, and burial to protect from trawlers or anchors, and the added measure of using sonar and other security measures to monitor and protect the cables and their landing stations. Specifically in the case of shallow water, cable burial not only protects it from direct sabotage or a dragged anchor, it also obfuscates the location of the cable. All these measures should be employed immediately to enhance the physical survivability of cable infrastructure from accidental and deliberate attack. 

Diplomatic Pressure: 

International legislation dating back to the Convention for the Protection of Submarine Telegraph Cables of 1884 established the preliminary basis for the protection of undersea cables. Subsequent legal instruments have been iteratively established and implemented globally, creating an uneven web of protective processes that varies sometimes significantly in scope and enforcement. More robust diplomatic cooperation is required to address the critical national security implications of undersea cable infrastructure vulnerability. A coordinated international legal framework with standardized enforcement procedures would enhance deterrence against potential saboteurs. Comprehensive legal and diplomatic frameworks for the security and defense of undersea cables would also serve as a clear signal to would-be aggressors that the international community is organized to impose consequences on perpetrators of cable attacks. 

Consequences for cable sabotage or disruption should include mandatory financial restitution mechanisms whereby states would be held financially liable for damages caused by vessels operating under their flag, regardless of whether malicious intent can be conclusively proven. In addition, this proposed framework should establish responses that include multilateral sanctioning, restricted access to international maritime resources, and exclusion from international telecommunications governance bodies for non-compliant states. Both the European Union, through its Critical Infrastructure Protection Directive, and the United Nations, via the International Telecommunication Union and the International Maritime Organization, are well positioned to organize this multilateral response and to exert the necessary diplomatic pressure to establish a cohesive international regime for undersea cable protection. 

National Resilience and Individual Preparedness 

The increasing sophistication and likelihood of sabotage operations targeting undersea cables demands a proactive approach firmly rooted in historical understanding and forward-looking resilience planning. The historical record demonstrates that undersea communication infrastructure has consistently been targeted during periods of international tension and conflict since the late nineteenth century. What distinguishes the contemporary threat environment is the potential for global impact from even limited disruptions, given the unprecedented dependence on these systems; information technology and communications networks, for example, are key extensions of undersea cable and without doubt form vital interdependent systems that are vulnerable to such disruptions. While no single solution can guarantee complete protection against determined adversaries, a comprehensive resilience-based framework offers the most robust defense against both immediate and cascading effects of disruptive cable attacks. 

To counter the evolving threat, international investment and development must focus on four key areas that historical analysis suggests are most effective: enhancing monitoring and surveillance capabilities, fostering international cooperation through formal agreements and joint operations, employing advanced cable hardening techniques, and leveraging diplomatic pressure to establish clear consequences for aggressors. By prioritizing these measures within a coherent national resilience strategy, the United States and its allies can significantly enhance the security of global undersea cable infrastructure. Infrastructure protection efforts—from World War I telegraph cable security to Cold War submarine detection systems—demonstrate that multi-layered, adaptive approaches consistently outperform single-focus strategies. In an increasingly uncertain strategic environment characterized by hybrid warfare and gray-zone operations, protecting the invisible backbone of global communications represents not merely a technical challenge but a fundamental requirement for maintaining international security and economic stability. 

Public concern and anxiety would likely increase during a deliberate information blackout, particularly if it extends beyond brief periods. Western societies have developed deep dependencies on digital connectivity for many daily functions, from banking to communications, making temporary disruptions increasingly problematic to normal operations. While creating conditions for panic and civil disobedience may not be the primary driver of sabotage, it could be an insidious aspect of a cable attack, especially if such an attack coincides with other disruptive attacks. It does not have to be so. Sweden and Finland, for example, have done credible work to prepare their citizens for crisis or war and total defense. The key points in the Nordic model of national resilience emphasize drawing individuals, communities, societies, and governments together into a cohesive unit that is robust and capable of dealing with strategic shock and panic without completely collapsing. Both models emphasize a social posture that insulates against disinformation and misinformation and places a high premium on home preparedness. 

There is a fundamental lesson for the rest of the West in thinking about resilience through the Swedish and Finnish model: be as prepared ahead of time as one can, such that panic does not take over when something serious inevitably happens. No solution to cable sabotage will be perfect, and a determined adversary will doubtless find ways to circumvent measures used to insulate cables from attack. But the resilience framework and the Nordic examples outlined above offer a multitude of alternatives to panic and economic destruction in the event of major disruptive cable attacks. 

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