Severed connections

A string of disruptions to undersea cables in the Baltic and South China and Red Seas has heightened concerns over the security of critical infrastructure.

Nov 12, 2025

Snip! Snap! Snip! the scissors go;
And Conrad cries out - Oh! Oh! Oh!
Snip! Snap! Snip! They go so fast;
That both his thumbs are off at last.

From the The Story of Little Suck-a-Thumb, Straw Peter

In mid-August, Finnish prosecutors charged the captain and two officers of the Eagle S, a tanker linked to Russia’s “shadow fleet”, with sabotage. They stood accused of using their anchor to sever five undersea cables linking Finland and Estonia, causing at least €60 million in damages. The vessel, fresh from a Russian port of Ust-Luga, was filmed by underwater drones near the mangled lines, its anchor conspicuously missing. Helsinki suspects the incident was a hybrid operation, part of a pattern of “accidents” targeting Baltic infrastructure since the war in Ukraine began. Moscow denies involvement.

The recent targeting of cables in the Gulf of Finland was hardly an isolated incident. A series of attacks against undersea cables around the world between 2024 and 2025 has raised alarms in capitals around the world. Severed subsea cables from the Baltic Sea, around Taiwan, and the Middle East were not accidental. Rather, they point to a quiet but intensifying struggle beneath the waves led by but not exclusive to authoritarian states probing the vulnerabilities of their adversaries’ infrastructure. The geopolitical implications of these events are sobering.

Intelligence agencies are adamant that hybrid threats are expanding from land and space to the seabed. As a result, many Western democracies are rethinking how they can protect the unseen arteries of the modern world. But what exactly are these cables? Why do they matter so profoundly? Where have the latest acts of sabotage occurred, and to what end? Most critically, how can nations and companies shift from benign neglect to robust protection of the world’s digital lifelines?

The cables that shrunk the world

Royal watchers may recall 1837 as the year Queen Victoria ascended the British throne. Her reign left an indelible mark on history. However, a far less heralded event that same year was arguably even more consequential: the laying of the first telegraph cables. Overshadowed by coronation fanfare, this quiet innovation sparked a communications revolution that would shrink empires, redraw maps and herald the birth of the modern information age.

First subsea telegraph lines (1871)

Source: G.W. & C.B. Colton & Co. (1871)

Until the middle of the nineteenth century, humanity’s ability to communicate across distance had depended on the stamina of horses and the homing instincts of pigeons. The arrival of the telegraph changed all that at the flick of a switch, transforming electrical pulses into messages that could traverse continents in seconds. By 1858, the first transatlantic cable stitched together Europe and North America, collapsing time and space in a single engineering feat. The implications were profound: diplomacy accelerated, markets synchronized, and the world began its march toward real-time interconnection.

Global telegraph cable system (1901)

Source: Telegraphic Code 5th Edition (1901)

Cable communications underwent three major innovations over the next 150 years: the invention of telephony in the late 1800s, the launch of transcontinental phone service in 1915 enabled by vacuum tube amplifiers, and most significantly, the exponential leap in capacity brought by fiber optic cables in the 1960s, enhanced by the boosting power of cerium, a rare earth element. This last breakthrough transformed data transmission by using light pulses through glass or plastic fibers to move vast volumes of data at unprecedented speed.

The first subsea fiber optic cable, TAT-8, was laid across the Atlantic Ocean in 1988 by a consortium led by AT&T, British Telecom, and France Télécom connecting the UK, France and the US. It marked a historic leap in global communications, offering vastly superior capacity and reliability over earlier copper-based systems. Today, billions of people around the world depend on over 1.4 million kilometres of undersea cables spanning the ocean floor (most of them buried). That’s enough to circle the earth 35 times.

Submarine cables around the world (2025)

Source: Submarine Cable Map (2025)

The backbone of the global economy

Subsea cables are the unsung backbone of the global economy. Over 99% of all intercontinental information traffic from financial transactions and military communications to video calls and tiktok videos flows through a vast network of more than 550 active fiber-optic cables. These slender strands, often no wider than a garden hose, transmit data at nearly the speed of light, linking stock exchanges and command centers in real time. Each day, an estimated $10 trillion in financial transfers rides these submerged arteries, rendering them not only critical infrastructure, but a strategic asset whose disruption could paralyze global commerce.

This underwater network supports almost every sector imaginable. Banks depend on them for instantaneous financial transactions, technology giants like Google, Amazon, and Microsoft rely on them to connect data centers worldwide, and governments transmit sensitive diplomatic and intelligence snippets via these hidden channels. Key operators include telecommunications companies such as AT&T and Vodafone, as well as specialist infrastructure firms like Alcatel Submarine Networks, NEC, and SubCom.

Yet, despite their immense geostrategic importance, subsea cables remain surprisingly fragile and exposed. Historically, cables have been accidentally damaged by natural deterioration, unintentional anchor dragging, fishing trawlers, and even seismic activity. As the Finnish prosecutions make clear, however, intentional sabotage is now viewed as the primary threat. Countries like Russia and China, alongside non-state actors, recognize the potential disruption that can be achieved by targeting these cables. Severing them, even temporarily, can trigger cascading global communication failures and isolate nations both economically and militarily.

A target-rich environment

A string of disruptions to undersea cables in the Baltic Sea has heightened concerns over the security of critical infrastructure. Since October 2023, at least 11 subsea cables have been damaged across the region. In November 2024, the C-Lion1 cable between Finland and Germany which carries 120 Terabytes per second and the BCS East-West Interlink between Lithuania and Sweden were severed almost simultaneously, raising suspicions of coordinated sabotage. The cutting of the BCS cable led to it being taken out of service prematurely.

Source: Statistica (2024)

In December 2024, Finland accused Russia of cutting an undersea cable linking Finland and Estonia, further escalating tensions. In most other cases, there have been no legal consequences to these incidents. But two days after the event, Finnish police boarded the Eagle S, the suspect vessel, and arrested the captain and crew members. In August 2025, the Finnish Prosecutor General brought charges of aggravated criminal damage and, more importantly, aggravated damage to the telecommunications network. The defendants are disputing the charges, saying that the cables broke in waters outside Finland’s jurisdiction. The prosecution has argued that they were dragged from within the country’s jurisdiction. When the case comes to trial, intelligence agencies from across the world will doubtless follow it closely.

The Indo-Pacific region too has registered multiple incidents involving suspected sabotage of undersea cables, notably around Taiwan. In January 2025, the Shunxing 39, Cameroon-flagged but operated by a Chinese firm, reportedly cut the Trans-Pacific Express cable near Keelung in the very north of the island after disabling its tracking systems. Between 2018 and 2023, Taiwan recorded over 50 similar incidents, largely attributed to Chinese fishing and cargo vessels. China’s deployment of civilian boats, all part of a shadow fleet operating under multiple identities and foreign flags, enables plausible deniability for state-backed operations.

And in September 2025, Internet access across parts of the Middle East, Asia, and East Africa was severely disrupted after multiple undersea cables in the Red Sea were damaged. At least four major cables carrying around a quarter of traffic between Asia and Europe were affected, causing outages and slower connections in countries including India, Saudi Arabia, and Djibouti. The cause of the cuts remains unclear, though authorities are investigating possible links to ongoing security tensions in the region including Yemen’s Houthi revels. Repair work is expected to take weeks given the logistical challenges of operating in contested waters.

Chokepoints and chain reactions

A glance at the global subsea cable map reveals the contours of digital power. Dense clusters of cables trace the outlines of North America, Europe, and East Asia, the nerve centres of global commerce, politics and defense. In stark contrast, large swathes of Africa and the Americas appear as digital backwaters, their sparse connectivity reinforcing economic marginalization. Meanwhile, the balance of cable ownership has shifted. Once the preserve of state-backed telecom consortia, subsea infrastructure is now increasingly bankrolled and controlled by tech titans like Google, Meta, Microsoft, and Amazon that view cable dominance not merely as bandwidth insurance but as strategic leverage in a digital arms race.

These shifts have sharpened strategic vulnerabilities. Technology firms, for all their digital prowess, possess limited experience in safeguarding physical infrastructure, an arena once dominated by national telecoms steeped in redundancy planning and defensive protocols. Their stewardship often lacks the rigorous security regimes historically maintained by state-backed operators. As ownership consolidates into the hands of a few powerful firms, systemic risks deepen. A well-aimed strike against a single cable operator could ripple across continents, making these digital arteries ever more alluring targets in an age of hybrid war.

State-backed sabotage is an acute concern. Intelligence communities warn of increasingly aggressive covert activities by Russia’s naval assets, notably submarines designed explicitly to interfere with underwater infrastructure. NATO and Western governments have heightened surveillance around key cable landing points in response. Similarly, China’s assertive expansion into undersea infrastructure, particularly via state-affiliated companies, prompts apprehension in Washington and European capitals. The U.S. government has actively discouraged international partnerships involving Chinese companies, citing espionage risks.

It is not only adversaries of the West who have shown a willingness to exploit vulnerabilities beneath the waves. The sabotage of the Nord Stream 2 gas pipeline widely believed to have been carried out by a Western state or an allied actor, serves as a stark reminder that covert attacks are hardly confined to autocracies. Though not a communications cable, the incident reveals that the West, no less than its rivals, recognizes the potency of subaquatic disruption in the grey zones of conflict. Indeed, plausible deniability cuts both ways.

Strategically positioned cables are especially susceptible in periods of heightened geopolitical competition. Maritime chokepoints such as the Strait of Malacca, Suez Canal, or coastal approaches near major financial centers pose high-value targets. A coordinated strike at these critical junctures could trigger significant global disruption. Security experts are urging enhanced protections at these chokepoints, incorporating surveillance sensors, autonomous drones, and rapid-response naval forces.

Securing the subsear frontier

Safeguarding the world’s undersea cables is an urgent, and fiendishly complex, task. They crisscross contested waters and sovereign jurisdictions, rendering clear legal responsibility murky at best. Securing them demands a scale of international cooperation rarely seen outside wartime alliances. NATO has made a start, deploying joint surveillance measures in the North Atlantic.

Yet in the Indo-Pacific and much of the Global South, protective efforts are embryonic, fragmented, and underfunded. The NorthSeal initiative, a nascent maritime security platform among North Sea states, offers one template. But meaningful progress will hinge on real-time maritime monitoring such as satellite tracking, automated identification systems, sub-sea sensors and drones and the integration of cable defence into NATO, EU and Indo-Pacific security doctrines.

Critical infrastructure resilience are the watchwords. Governments and technology giants alike are scrambling to diversify subsea cable routes, embed redundancy and invest in next generation infrastructure equipped with interference-detection technologies. While worthwhile, such measures often lag behind soaring data demand and rising geopolitical friction. Ultimately, much of the world remains perilously reliant on single points of failure where a single cut can sever entire nations from global networks.

Systematic stress testing and scenario planning must become routine. So too must an expansion of cable repair capacity: fewer than 60 cable-laying and repair ships ply the globe, and bottlenecks are acute in the southern hemisphere. Without pre-positioned fleets and streamlined response protocols, outages can persist for weeks, with consequences measured not merely in lost connectivity but in financial and diplomatic disruption.

Once invisible, the seabed has become the newest theater of great-power competition. Like the railroads, shipping lanes, and telegraph lines of past centuries, undersea cables are critical infrastructure, integral not just to economic function but to national security itself. They are also projected to expand in length by almost 50 percent by 2040. Protecting them will require more than innovation: it demands the political will to treat subsea infrastructure as core security assets. Failure to do so risks not just service outages, but cascading crises with the power to upend diplomacy, disrupt markets, and fracture alliances, all beneath the surface.

Success also hinges on serious public–private cooperation. Tech firms, telecom operators and security agencies must fuse intelligence-sharing with joint investments in surveillance and rapid response. For all the marvels of the digital age, its arteries remain alarmingly fragile. Without urgent action, the next strike against these unseen lifelines may not just interrupt internet service, but ignite a geopolitical conflagration, quietly unleashed beneath the waves.

Robert Muggah is a principal of SecDev, a geopolitical risk company based in Ottawa, where he oversees the geopolitics and forecasting portfolio. He is also the co-founder of the Igarape Institute, advises venture capital and technology companies, and contributes to the annual Global Risk Report of WEF.

Misha Glenny is an award-winning journalist and author of six bestselling books, including McMafia (now a BBC/AMC series) and DarkMarket, focusing on organized crime, cybersecurity, and geopolitics. A former BBC correspondent who has won the Sony Gold Award for Excellence in Broadcasting and the BT Award for Security Journalist of the Year, he has held academic positions at LSE, Columbia, and UCL. He currently serves as Rector at the Institute for Human Sciences (IWM Vienna) - Central Europe’s leading ideas incubator in the social sciences.