Subsea cable and its growing stretch
The subsea cable plays a critical role in global communication and geopolitical power dynamics. Around 99% of the global data are transmitted through subsea cable, making them vital for internet connectivity and international finance. The development of the subsea cables have been shaped for 180 years by private sector firms and international companies. The first subsea cables were developed in the 1820s by an attaché to the Russian Embassy in Munich to send electric telegraph communications. However the significance attached to subsea cable has never been linear in history. The rise of radio communication in the 1930s which was later followed by the prevalence of satellite communication between the 1960s and late 1980s. In the 1990s, the demand for the high-volume of information facilitated the resurgence of cables. As of 2024, there are 559 cable systems and 1,636 that are currently active or under construction. Between 2023 and 2025, a new cable boom valued at a record $10 billion will bring an estimated 78 systems online measuring over 300,000 kilometers in length, which has not been seen in over 20 years.
The significance of the subsea cable stems from the fact that they are the basis of global digital interconnectedness. They not only define which areas of the world are connected but also how these areas are connected (e.g., speed, bandwidth), and who controls those connections (e.g., the companies building the cables, the companies managing the “landing points” that link the cables to shore). Once these cables reach land, they either connect directly to users or link to the data centres that power cloud services and critical infrastructure.
Therefore, companies that direct the deployment of the subsea cables produce geopolitical effects on internet connectivity and everything that comes with it, including scientific research, digital trade and government and personal communications. To put precisely, states are not the sole custodian player or owner when it comes to laying subsea cables and hence, this arena has never been strictly controlled by the state. Ownership of cables are blended across nationalities and locations. As of 2021, the U.S. Company SubCom, French firm Alcatel and Japan’s Nippon Electric Company (NEC) collectively hold 87% of the global subsea cables and China’s HMNT (Huawei Marine Network Technologies) holds 11% of the same.
In terms of speed, these cables push through terabits of information per second, compared to a gigabit of data per second transmitted through satellites. For instance, Google has invested $47 billion to improve Google Cloud infrastructure by investing in approximately 14 subsea cables. In November 2024, Google announced its plan to invest in two subsea cables connecting Australia and Christmas Island.
In addition, given the fact that subsea cables are a part of a state’s critical infrastructure, there is a strong element of interdependence among the system of subsea cables. It means that a break in one cable can have a cascading effect on internet access to distant states. Given the technological supremacy and the tendency among the U.S. and China to exert its influence over the same, has already flamed the existing tech-war to the sphere of undersea cables. For instance, the U.S. has been leveraging technology diplomacy to dissuade other states from partnering with Chinese firms like HMN technologies, formerly Huawei Marines. As a countermeasure, China is engaged in developing its independent subsea cable network which would link China and Hong Kong with multiple Southeast Asian states.
Given the immense importance which is attached with undersea cables, on 22 March 2025 it was reported that China Ship Scientific Research Centre (CSSRC) and its affiliated State Key Laboratory of Deep-Sea Manned Vehicles have developed a ship to cut cables lines at depth of up to 4,000 meters (13,123 feet)
Existing International law backing subsea cablesÂ
The earliest legal set of rules was laid down by the 1884 Convention for the Protection of Submarine Telegraph Cables (1884 Cable Convention). It is the only convention dealing with the protection of subsea cables and is valid till date. The International Cable Protection Committee (a non-profit organisation) was created in 1958. It is guided by the vision “to be the international submarine cable authority providing leadership and guidance on issues related to submarine cable security and reliability”. It carries out various activities to promote subsea cable security. The rules and regulations of the ICPC are laid out in accordance with the United Nations Convention on the Law of the Seas (UNCLOS).
In accordance to the principles laid by the UNCLOS, there are certain sections which addresses the rights and issues related to laying undersea cable:
- Articles 79 and 112 have defined the freedom to lay and maintain submarine cables,
- Articles 87 and 147 have noted the obligation of “due respect” or “responsible regard” for other activities,
- Articles 113 to 115 have addressed the protection of submarine cables on the high seas (these articles are based on the three articles listed in the 1884 Cable Convention) and
- Part XII has defined the obligation to protect and preserve the marine environment.
However, the freedom to lay undersea data cables is not unlimited. According to Article 112 (2) of the UNCLOS, it is noted that states need to have due regard to other existing cables and not jeopardise their repairing or any existing pipeline. Second, states should also take into consideration the interest of other states in regard to their exercise of high seas freedom and deep seabed mining.
Gaps in International laws governing Subsea cables
Despite codification of laws pertaining to undersea data cable, there are significant gaps. Firstly, given the fact that the undersea data cable is laden with economic and strategic significance and is a part of the critical infrastructure of states, it is highly susceptible to disruptions. It ranges from damages caused during fishing and mining of natural resources, intentional damage and cyber-attack.
Second, although the existing laws address the states, there is a significant presence of private players who have established a strong presence in the arena of laying subsea cables. The realm of the existing law needs to be expanded to address the private players as well.
Thirdly, another complex issue is that there is no set of laws which acts as a mechanism for the state to address such vulnerabilities. Perhaps, the existing lacuna points at the need for greater collaboration among private players and states.
Lastly, James Kraska has rightly pointed out that the existing laws have not addressed the issue of how subsea cables can be used by states or non-state actors as a pawn to inflict irrevocable damages. The situation becomes more serious both during conflict and war.
Although the rules set forth in the Oxford, San Remo and Oslo Manuals which have prohibited destruction or cutting of cables of neutral states during the state of war and have given states the right to pursue protective measures against the destruction of cables; have failed to widen its scope to address the destructive activities of non-state actors like terrorist groups which can directly or indirectly cause damage to the subsea cables.
For instance, while the Houthis were attacking ships in the Red Sea (since November 2023), it has indirectly damaged a number of subsea cables after a listing vessel dragged its anchor. In addition, crippled state of the cable-maintenance industry exacerbates the disconnect between the demand and supply for maintenance ships which normally increases the repair time to 40 days.
Therefore given the complex scenario, the existing laws fall short to address the vulnerabilities of the subsea cables.
Increasing Geopolitics behind subsea cables
The world is already connected by the subsea data cables and its vitality is stated above. Since 2018 there is an increasing trend in regard to undersea data centres. It is built around the rationale that the ocean floor is comparatively conducive to land for overall reliability of datacenters. Since datacenters on land are highly susceptible to corrosion from oxygen, temperature, natural calamities and high cost of maintenance, hence underwater datacenters provide a better alternative both in terms of maintenance, energy sustainability and cost efficiency.
Underwater Data Centers
According to the International Energy Agency (IEA), there are approximately 8,000 data centres and about 33% and 10% are located in the U.S. and China respectively. It was in 2018 when Microsoft under its Project Natick had deployed the Northern Isles datacenter at the European Marine Energy Centre, off the coast of Scotland. At the deployment site, a cable containing fibre optic and power wiring was connected to power the datacenter.
In 2023, the Chinese private company Highlander China built the world’s first commercial underwater data centre. The facility is located off the coast of Sanya on Hainan Island, aims to harness the power of cold seawater to slightly cool its operation and reduce overall energy consumption. On 19th February 2025, China created another underwater data centre with enough computing strength to support 7,000 conversations with DeepSeek per second.
However, in recent times it is alleged that China has made a breakthrough in deep-sea-cable cutting technology which is capable of cutting subsea communication cables at depths up to 4,000 meters. Although the device is still in its testing stage, its deployment in the future would significantly escalate hybrid warfare capabilities. The situation will be comparatively dire in those areas where China has strategic interests such as the Taiwan Strait.
Moreover, given the dependence of functionality between the subsea data cables and underwater data centers, there is a probability that deployment of such technology can be used as a bargaining tool by China in the future.
On the other hand, repairing damaged cables can typically range from $ 1 million to $ 3 million. In addition the ambiguity of existing laws in aspects of subsea cable disruptions in the international waters, makes the overall governance of the same unfeasible. Disruptions of strategic cables and landing stations would sent shock waves through global markets.
Hence, given a gist of the importance of subsea cables to states’ critical infrastructure, existing laws, deployment underwater data centers and existing dangers; it is time for the international laws to address the existing lacunas. The growing global dependence on critical infrastructure can only be secured when the international laws are curated to support the same.
