The vulnerability of underwater critical infrastructure, especially submarine cables, has emerged as a focal point amid escalating geopolitical tensions. Recent attacks, particularly in the Baltic Sea, underline the need for advanced measures to safeguard global digital connectivity.

One of the many facets of the ongoing Russia Ukraine war has been the focus on underwater critical infrastructure. A number of incidents have been reported-recorded, and these highlight the fact that over one million miles of cables crisscross on the seabed across the globe and carry nearly 95 percent of data. These are undefended and highly vulnerable. Furthermore, these are attractive and potent targets for disruption-destruction and require new approaches to physical and digital protection.

The Baltic Sea in particular has witnessed incidents of attack on fiber optic cables in the last two years. In 2023, the EE-S1 and Balticconnector was damaged and in November 2024, two incidents involving C-Lion1 (between Finland and Germany) and Estlink 2 (between Sweden and Lithuania) were damaged.  So far no conclusive evidence has been made public about the ships responsible for these disruption; but Chinese ship Yi Peng 3 was arrested and Swedish government agencies conducted enquiries. However the ship “continued its voyage” and to Port Said in Egypt. The other reported attacks in the Baltic Sea include one each in 2008 and 2011.

The recent statement by the European Commission and the High Representative on the Investigation into Damaged Electricity and Data Cables in the Baltic Sea  has accused Russia of intentionally destroying Europe’s critical infrastructure by vessels belonging to the Russia ghost fleet.  The statement further reiterated the groupings commitment to “resilience and security of critical infrastructure” as also “strengthening efforts to protect undersea cables, including enhanced information exchange, new detection technologies, as well as in undersea repair capabilities, and international cooperation”.

The European fears and responses thereof are quite natural given that Russia had accused the West of complicity in the blowing up of the Nord Streams. In this context, Former Russian President Dmitry Medvedev  warning merits mention: “from the proven complicity of Western countries in blowing up the Nord Streams” has compelled Russia to  resort to thinking about “destroying the ocean-floor cable communications of our enemies”.

EU foreign policy Chief Kaja Kallas has warned that the attacks on undersea cables in the Baltic Sea are not isolated incidents, but are “part of a pattern of deliberate and coordinated actions to damage our digital and energy infrastructure.”  Moscow has dismissed Western and NATO allegations and insinuations, and called these as fake and fabricated and meant to malign the reputation of the country. Russia has also been accused of resorting to hybrid warfare and Gray Zone Operations.

Operational responses

The Baltic Sea incidents prompted at least two navies to commence patrols in the Baltic Sea. In a recent incident, a Russian merchant vessel Eagle S, an old tanker suspected to be part of Russia’s shadow fleet, was arrested by the Finnish Coast Guard. It was marshalled to Finland’s waters for investigation for “aggravated interference with telecommunications, vandalism, and regulatory offenses” for causing an outage of the Estlink 2 undersea power cable. Apparently, the vessel had transited over the 658 megawatt undersea power cable connecting Finland and Estonia, dragged the cable nearly almost 62 nautical miles . It is averred that “through underwater research” it was clear that the Eagle S had dragged its anchor for nearly 100 kilometers resulting in damages.

The Eagle S incident prompted Estonia to launch naval patrols to protect Estlink 1, a parallel electricity carrying cable.  Earlier, in an incident in 2022, the Nord Stream gas pipeline on the seabed between Russia and Germany was blown up and the incident is still under investigation. More recently, Yantar, a Russia auxiliary general oceanographic research vessel with underwater rescue capabilities  was escorted out of the Irish waters on suspicions that it could engage in damaging underwater internet cables between Ireland and the UK.

Gray Zone Operations

Gray Zone operations are fast gaining popularity among the navies. Unlike during the Cold War, where a definitive pattern of open sea warfare was the norm, the current trends are to operate just below the “threshold” to achieve strategic objectives keeping in mind that their actions do not attract a military reaction-response from the opponent.  The contemporary strategic literature has labelled such “situations and responses thereof” as Grey Zone operations and few regions/areas have been identified where Grey Zone operations are in vogue and being practiced. Grey Zone tactics are “ambiguous, belligerent, and coercive actions” because they do not adhere to the “traditional black-or-white dichotomy of war and peace; instead, they fall somewhere in the undefined middle.”

It is argued that damage-disruption of  underwater fiber optic cables is a part of the Gray Zone operations and  is an unconventional military response to achieve strategic aims without a military conflict. In fact the maritime law enforcement agencies are adequately equipped and therefore the best choice to respond to incidents relating to Gray Zone such as underwater fiber optic cables

Technological Solutions

The NATO is considering the development of HEIST (Hybrid Space/Submarine Architecture Ensuring Information Security of Telecommunications) that “combines the existing robustness of subsea cables with the flexibility and reach of satellite communication” and “provide resilience of communication infrastructure”. In the event of any disruption of the underwater fiber optic cable, the system will ensure “seamless switching between undersea cables and satellite links”.  Furthermore, it will locate the exact position where damage has taken place thereby reducing response time. It will also “increase the number of pathways for data transmission, including diverting high-priority traffic to satellites.”

This enables at least two robust pathways i.e. underwater and space thereby “enabling resilient communication is path diversity.” However the transmission speed through the HEIST is slow and is constrained by the fact that data transmitted through satellites is slow when compared with the submarine cables. HEIST plans to overcome this by using “higher bandwidth laser optics systems in their satellite links”; yet it “still falls short of what cables can do”. It is worth mention that “laser transmissions can be blocked by smoke, haze, clouds”.

It has been noted that “instead of requiring all of our data to flow through subsea cables,  we would like to enable an ecosystem of options…While one may argue that submarine communication cables are very efficient, they are not very resilient to natural or human-made threats.”

The HEIST was launched in July 2024 at a cost of US $ 2.5 million and is partially supported by the NATO’s Science for Peace and Security programme (SPS). It brings together “Allies, prominent institutions including the Cornell, John Hopkins Bifröst, and Swedish Defence Universities and the Swiss Federal Institute of Technology as well as telecommunications companies to address the urgent need for a more resilient internet infrastructure worldwide,”

India and Underwater Digital Infrastructure

The current state and future trends in digital penetration in India is quite promising. In January 2024, there were 1.12 billion cellular mobile connections (78.0 percent of the total population) in India, 462.0 million were using social media (i.e.32.2 percent of the total population), 751.5 million internet users (52.4 percent penetration). Nearly 17 international subsea cables landing in India at 14 distinct landing stations in Mumbai, Chennai, Cochin, Tuticorin, and Trivandrum.

Indian telecom operators involved in submarine cable infrastructure include:

Company                             Land Stn.         Location                                       Remarks

Tata Communications            5                          Mumbai, Chennai, and Cochin

Global Cloud exchange          2                          Mumbai and Trivandrum

Reliance Jio                              2                         Chennai and Mumbai                     new projects underway

Bharti Airtel                              2                         Chennai and Mumbai                     2Africa/EMIC-1;  SEA-ME WE 6

Sify Technologies-BSNL                                                                                                 Operation of landing stations

Vodafone and IOX                                                                                                           Puducherry under consideration

Source: Ministry of Communication, Government of India, 05 December 2024, https://pib.gov.in/PressReleaseIframePage.aspx?PRID=2081003

Safety, Security and Law Enforcement

Although the fiber optic cables are rugged and can withstand harsh underwater conditions (pressure, salinity, temperature) they are prone to damages hue to natural causes such as underwater earthquakes, marine life attacks (shark bites) and negligence / sabotage by humans. The threat of destruction-disruption of underwater critical infrastructure in essence is a law enforcement issue. For instance, in January 2024, the Chinese Coast Guard (Shanghai Headquarters) ordered investigation against a foreign vessel which was alleged to have anchored close to a protected area meant for submarine cables. The vessel was subjected to official investigation for “violating regulations for the protection of submarine cables and pipelines.”

Concluding Thoughts

In 2023, there were over two hundred submarine cable repairs tasks undertaken globally which clearly emphasizes not only the vulnerabilities but also the criticality of underwater digital infrastructure. The Indian government acknowledges the importance of resilience of underwater digital infrastructure noting that “disruptions to submarine cable systems can have far-reaching consequences” resulting in, among others, “ economic instability and security concerns” and interruptions  in internet access for large numbers of people.

Similarly, the Data Centre, which are fast emerging as an integral part of the digital infrastructure, are vulnerable to sabotage through “resonant frequency” acoustic attacks on hard drives, and “sound injection” attacks can make servers unresponsive, resulting in crashed networks. Similarly, espionage by devices-robots-saboteurs and suicidal attacks by mammals are potent tools for digital disruptions.