The War Beneath the Ocean: How Undersea Cables Became the New Battlefield
There are battlefields that dominate television screens: cities under missile attack, aircraft crossing contested skies, warships operating in formation and soldiers fighting across physical territory. There is another battlefield, however, that remains almost completely invisible to the public. It lies beneath the oceans, in darkness and at depths where sunlight disappears, and it contains infrastructure upon which modern civilisation increasingly depends. Thousands of kilometres of fibre-optic cables cross the seabed connecting continents, carrying the communications and data flows that underpin international finance, commerce, government, technology and the internet. For decades, these cables were largely treated as commercial infrastructure rather than strategic assets. That assumption is becoming increasingly difficult to sustain. The seabed is emerging as a new domain of strategic competition, where submarines, remotely operated vehicles, autonomous underwater systems, surveillance networks and critical infrastructure increasingly intersect.
The issue has acquired fresh urgency following reports of a Russian undersea operation near Svalbard. According to a Reuters report published on September 10, 2026, NATO allies including Britain, Norway and the United States intercepted and deterred a covert Russian operation in the Arctic earlier this year involving Russia's Main Directorate of Deep Sea Research, commonly known as GUGI. Western officials cited in the report said Russian deep-sea submersibles were involved in an operation associated with technology designed to disable critical undersea fibre-optic cables. Crucially, the cables were not damaged. That distinction matters. The incident should not be presented as a successful attack on Western infrastructure. Its significance lies elsewhere: in the reported testing and demonstration of a capability that could potentially be used against critical infrastructure during a future crisis.
That distinction also reveals something fundamental about modern strategic competition. A military capability does not become strategically important only after it is used in combat. The ability to threaten infrastructure can itself become a strategic instrument. If a state can locate, monitor, interfere with or potentially disable an adversary's critical communications infrastructure, it gains another means of exerting pressure without necessarily firing a conventional weapon. This is particularly significant in an era of grey-zone warfare, where states increasingly seek to achieve strategic effects without crossing the political threshold that would automatically trigger conventional military retaliation. The objective may be intelligence collection, mapping, preparation, deterrence, coercion, disruption or simply the demonstration that a vulnerability exists. The seabed is particularly attractive for such activities because it is difficult to observe continuously and because many of the systems located there are owned or operated by commercial entities rather than military organisations.
The Invisible Infrastructure of the Digital World
The modern internet is often imagined as something almost weightless. We speak about information travelling through the "cloud", as though data simply disappears into an invisible digital space. In reality, much of the world's international digital communication still depends on physical infrastructure. Fibre-optic cables cross oceans and connect countries, continents and data centres. They carry communications, financial information, commercial transactions and enormous volumes of internet traffic. NATO has described undersea cables and pipelines as critical infrastructure and has stated that more than 95 percent of global internet traffic travels through undersea cables. NATO has also highlighted the enormous financial value dependent upon these networks, citing estimates of roughly $10 trillion in financial transactions every day.
This creates a remarkable strategic paradox. The digital economy has become extraordinarily sophisticated, but some of its most important physical foundations remain exposed to the physical realities of the ocean. A cable may be technologically advanced, but it is still a physical object lying on the seabed. It has a route. It has landing stations. It has repair requirements. It passes through geographic areas that can be monitored, surveyed or potentially interfered with. The enormous geographic scale of the world's submarine cable network makes permanent military protection impossible. No navy can place a warship beside every kilometre of cable. Consequently, the protection of this infrastructure depends on surveillance, intelligence, commercial cooperation, maritime awareness, redundancy and the ability to respond quickly when something goes wrong.
That last point is particularly important because not every damaged cable is the result of sabotage. Fishing activity, anchors, shipping accidents, natural events and technical failures can all cause damage. This creates one of the central difficulties of seabed security: attribution. A state may know that a cable has been damaged without immediately knowing whether the incident was accidental or deliberate. Establishing intent can be considerably more difficult than establishing physical damage. In a grey-zone environment, that uncertainty can itself become strategically useful.
The Seabed as a Battlespace
For much of modern naval history, strategic attention focused on the surface of the ocean. Fleets fought for control of sea lanes, ports and maritime approaches. The arrival of submarines transformed the underwater environment into a major military domain. Nuclear-powered submarines subsequently introduced another dimension to strategic warfare, giving states the ability to operate beneath the ocean for extended periods and, in the case of ballistic-missile submarines, to maintain a survivable nuclear deterrent.
The strategic environment is now evolving again. The seabed itself is becoming important.
Pipelines, fibre-optic cables, power infrastructure, sensors and other systems are creating a new layer of strategic assets beneath the surface. The result is an increasingly three-dimensional maritime battlespace. Above the water are ships and aircraft. Beneath the surface are submarines and underwater vehicles. On or near the seabed are cables, pipelines, sensors and other infrastructure. A state seeking maritime superiority therefore has a growing incentive not merely to control the surface but to understand what exists beneath it.
NATO has recognised this changing environment. Following incidents involving undersea infrastructure in the Baltic Sea, the alliance launched Baltic Sentry in January 2025 to increase surveillance and deterrence around critical infrastructure. The initiative includes frigates, maritime patrol aircraft and naval drones, while NATO has also sought greater integration of national surveillance capabilities and cooperation with industry.
The importance of this development extends beyond the Baltic. It demonstrates a broader strategic shift: protecting undersea infrastructure increasingly requires a combination of military power, commercial information, surveillance technology and rapid attribution. NATO's Critical Undersea Infrastructure Network brings together civilian and military authorities, industry and specialists to improve information sharing, situational awareness and the detection of suspicious activity.
Russia and the Deep Ocean
Russia's GUGI occupies an especially interesting place in this discussion. The organisation's reported activities demonstrate why deep-sea capabilities have strategic value beyond traditional submarine warfare. Operating at great depths requires specialised vessels, submersibles, sensors and highly trained crews. The deep ocean is one of the few environments on Earth where even technologically advanced states face major difficulties maintaining continuous awareness.
That makes the deep sea attractive for intelligence collection and surveillance. A sophisticated underwater platform can potentially inspect infrastructure, map the seabed, monitor activity or conduct specialised operations while operating in an environment that is inherently difficult to observe. The strategic value therefore does not necessarily lie in physically cutting a cable. It can lie in knowing where the cable is, understanding its characteristics, identifying how it could be approached, determining how quickly it could be repaired and assessing how governments might respond to its disruption.
This is why reports of exercises involving potential sabotage technology deserve attention even when no infrastructure is actually damaged. Preparation can provide information. Information can produce options. And options create strategic leverage.
At the same time, responsible analysis requires avoiding the temptation to interpret every Russian underwater operation as preparation for an imminent attack. States conduct intelligence and military activities for many reasons, and the evidence available publicly is often incomplete. The important strategic observation is therefore not that a particular cable attack is inevitable. It is that the capability to threaten critical undersea infrastructure is increasingly becoming part of the broader competition between major powers.
Grey-Zone Warfare Beneath the Waves
The underwater environment is particularly suited to grey-zone activity because it combines strategic importance with ambiguity. Traditional warfare usually provides relatively clear signals. A missile strike is visible. An aircraft crossing a border can be tracked. A warship attacking another warship creates an obvious military event. Undersea infrastructure presents a very different problem.
Suppose a cable suddenly stops functioning. Investigators discover physical damage. The location is known, but the cause is uncertain. A vessel was operating nearby, but its presence may have been legitimate. An underwater drone was detected in the region, but its purpose is unclear. Intelligence agencies suspect deliberate interference, but the evidence is not immediately sufficient for public attribution. What should the affected state do?
This is the strategic space in which grey-zone operations thrive.
The purpose may be to remain below the threshold of open conflict while creating economic or political costs. It may be to test an opponent's surveillance capabilities. It may be to discover how quickly the opponent can detect suspicious activity. It may be to create uncertainty or to force the adversary to spend resources protecting infrastructure. Even when an operation produces no physical damage, it can reveal information about the defender's reaction.
This makes seabed security a problem for more than the navy. Intelligence agencies, coast guards, law-enforcement authorities, telecommunications companies, insurers, regulators, diplomats and lawyers all become part of the response mechanism.
Why the Arctic Matters
The Svalbard episode is especially interesting because of its geography. The Arctic is becoming increasingly important to great-power competition, and Svalbard sits in a strategically sensitive environment between mainland Norway and the wider Arctic region. The undersea infrastructure connecting Svalbard to mainland Norway has both civilian and strategic significance, while the broader Arctic environment is increasingly attracting military and technological attention.
The Arctic also demonstrates why geography matters even in an age of digital connectivity. Data may be global, but the physical infrastructure carrying that data remains geographically constrained. Cables must follow routes across seabeds. Landing stations must exist somewhere. Ships must navigate particular waters. Repair vessels must reach damaged sections. Consequently, digital infrastructure can create new strategic importance for locations that might otherwise appear remote.
The lesson is broader than Svalbard. Wherever critical infrastructure passes through a strategically important maritime environment, that infrastructure becomes part of the security equation.
The Indian Ocean Dimension
For India, this subject is particularly important because the Indian Ocean is simultaneously a major maritime theatre and an increasingly important component of global digital connectivity. India's economic growth, digital transformation, financial system and expanding data-centre ecosystem all increase the importance of reliable international connectivity. The physical infrastructure supporting that connectivity is therefore becoming an element of national resilience.
The Government of India stated in March 2026 that four submarine cable systems were under commissioning at Indian cable landing stations: India Europe Xpress, SEA-ME-WE-6, 2Africa and the Raman Cable. The government also listed three additional systems under planning: the Wyasa Cable System, Indian Ocean Cable and WABAN. The listed landing locations include Mumbai, Chennai and Raigad.
This expansion is strategically significant. India's digital economy is becoming more dependent on a web of international physical connections, and those connections increasingly intersect with the country's maritime security environment. A cable landing station is not simply a telecommunications facility. It is a physical point at which global digital infrastructure meets national territory. The cables approaching it cross maritime spaces that must be monitored and protected.
This does not mean that India should militarise every cable or treat every maritime incident as hostile. It means that subsea infrastructure should increasingly be viewed through a resilience framework. India needs redundancy, rapid repair capabilities, maritime domain awareness, cooperation between government and industry, and the technological capacity to detect unusual activity around critical infrastructure. The protection of India's digital economy is no longer solely a cyber-security problem. It has a maritime component.
The Technology of the Future Underwater Battlefield
The most interesting development may be the emergence of networks rather than individual platforms. The future of seabed security is unlikely to depend solely on large submarines or surface warships. Instead, it is likely to involve combinations of satellites, aircraft, surface vessels, submarines, autonomous underwater vehicles, remotely operated vehicles, seabed sensors and artificial intelligence.
Each system provides only part of the picture. A satellite may detect unusual surface activity. A patrol aircraft may identify a vessel operating in a sensitive area. A surface ship may deploy an underwater drone. A seabed sensor may detect an unusual acoustic signature. Commercial shipping data may establish that a particular vessel spent an unusual amount of time in a specific location. Artificial intelligence can then help analysts combine those separate pieces of information into a coherent picture.
NATO is already exploring this model. Its Baltic Sentry activity has incorporated maritime drones and additional surveillance technologies, while NATO's Allied Command Transformation has described the seabed as an increasingly contested environment and highlighted the potential of uncrewed systems and artificial intelligence in maritime vigilance.
This suggests that the future undersea contest may be less about who possesses the largest submarine and more about who can build the best underwater awareness network. The strategic advantage will belong to the state that can see more, understand more and respond faster.
The Legal and Political Problem
Technology alone cannot solve the problem. The legal environment surrounding undersea infrastructure is equally important.
International maritime law provides extensive rules governing activities at sea, but grey-zone operations can exploit the space between clearly lawful activity and clearly hostile action. A vessel approaching a cable is not automatically committing an offence. A ship conducting underwater surveys is not necessarily preparing an attack. A cable being damaged does not automatically establish who caused the damage or why.
This makes evidence and attribution central to any response.
A government that reacts too aggressively to an ambiguous incident risks escalation based on incomplete information. A government that reacts too cautiously may encourage further probing. The strategic challenge is therefore to develop enough surveillance and investigative capability to reduce uncertainty before political decisions have to be made.
There is also an important question of responsibility. Much of the world's undersea infrastructure is commercially owned. Governments may provide security, but private companies operate and maintain many of the assets. This means that protecting the seabed requires a public-private security architecture rather than a purely military one.
The NATO experience demonstrates this shift. Its Critical Undersea Infrastructure Network explicitly brings governments, military organisations, industry and technical experts together because no single institution possesses all the information or capabilities required to secure the infrastructure.
The Strategic Lesson
The most important lesson from the growing focus on undersea cables is not that the oceans are about to become a new battlefield in the conventional sense. It is that the definition of strategic infrastructure is changing.
National security was once largely associated with territory, military bases, ports, energy supplies and communications centres. Today, the strategic map is much larger. It includes satellites, data centres, cloud infrastructure, semiconductor supply chains, energy networks and undersea cables.
The vulnerability of these systems demonstrates an uncomfortable truth about modern technological society: the more dependent we become on invisible networks, the more important their physical foundations become.
The cloud has a seabed.
The internet has landing stations.
Global finance depends upon physical communications infrastructure.
And a significant part of the world's digital economy ultimately depends upon cables lying in the darkness beneath the sea.
That is why the seabed deserves strategic attention.
The Battlefield Nobody Sees
The most consequential battles of the future will not necessarily resemble the battles of the past. A strategic confrontation may begin not with an invasion but with disruption. It may involve information rather than territory, infrastructure rather than military bases, or ambiguity rather than an openly declared act of war.
Undersea cables sit directly at the intersection of these trends.
They are physical infrastructure in a digital economy. They are commercial assets in a strategic environment. They are civilian systems that can carry information essential to governments and economies. They are spread across vast distances and are difficult to monitor continuously. And when something goes wrong, determining whether it was an accident or an act of deliberate interference can itself become a strategic challenge.
The recent Svalbard episode therefore deserves attention not because it proves that a new underwater war has begun, but because it illustrates where strategic competition is moving. Russia's reported deep-sea activity, NATO's expanding surveillance efforts, the development of naval drones and underwater monitoring systems, and the growing dependence of economies on subsea infrastructure all point in the same direction: the seabed is becoming strategically important.
For India, the lesson is particularly clear. As India's submarine cable network expands and its digital economy becomes increasingly interconnected with global systems, maritime security and digital security will become more closely linked. Protecting India's digital future will require not only firewalls and cyber-defence but also ships, sensors, surveillance, redundancy, repair capability, intelligence and a clear understanding of the maritime environment surrounding the country's critical infrastructure.
The next strategic contest may therefore be fought in places most people will never see.
Far below the waves.
Along the ocean floor.
Around cables that look ordinary but carry extraordinary strategic value.
The battlefield may be invisible.
The consequences will not be.
Strategic Vanguard
Geopolitics | Defence | Strategy
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