Introduction
It is a common misconception that the global internet is powered by satellites; in fact, over 95% of all international data travels through a vast network of submarine fibre-optic cables laid on the ocean floor (UNEP, 2009). These cables are the invisible highways of the modern world, carrying everything from financial transactions worth trillions of dollars daily to sensitive government and military communications (Runde et al., 2024). While essential to the global economy and national security, this critical infrastructure is highly vulnerable. The protection of these cables presents a complex challenge that is not merely technical but also legal and geopolitical. This essay will argue that the existing international legal framework for the protection of submarine cables, primarily the United Nations Convention on the Law of the Sea (UNCLOS), is insufficient to address the threats posed by modern geopolitical competition and the rise of ‘grey-zone’ activities. While UNCLOS provides a foundational set of rules, its state-centric design and enforcement mechanisms are ill-equipped for an era of hybrid warfare and the complex involvement of private corporate actors.
The Foundations of International Cable Protection
The history of international law concerning submarine cables dates back to the 19th century, long before the advent of the internet. The first major international agreement was the 1884 International Convention for the Protection of Submarine Telegraph Cables (the Paris Convention). This treaty established the foundational principle that damaging a submarine cable is a punishable offence. Article II of the Convention makes it an offence to “break or injure a submarine cable, willfully or by culpable negligence,” establishing a clear legal norm against such interference (Paris Convention, 1884). The Convention also introduced principles of liability for damage caused during the laying or repair of other cables (Article IV) and a compensation scheme for mariners who sacrifice fishing gear or anchors to avoid damaging a cable (Article VII).
These principles were later incorporated into the primary modern treaty governing maritime activities, the 1982 United Nations Convention on the Law of the Sea (UNCLOS). UNCLOS is often referred to as the “constitution for the oceans” and provides the main legal framework for submarine cables today. It affirms the right of all states to lay submarine cables on the high seas (Article 112) and on the continental shelf (Article 79). Critically, it also carries forward the obligation for states to criminalise the intentional or negligently damaging of cables. Article 113 of UNCLOS requires states to adopt laws making the breaking or injury of a submarine cable a punishable offence for ships flying their flag or persons subject to their jurisdiction. This framework establishes a clear right to install this infrastructure and a corresponding duty on states to prevent its damage.
Jurisdictional Gaps and the Challenge of the ‘Grey Zone’
Despite the rules established in UNCLOS, the legal framework suffers from significant gaps, particularly regarding enforcement. The primary enforcement mechanism under UNCLOS is flag state jurisdiction, meaning that the state where a vessel is registered is responsible for prosecuting offences committed by that vessel on the high seas. This model creates a major loophole in an era of geopolitical competition. If a state wishes to conduct a deniable attack on another state’s infrastructure, it can use a vessel flying its own flag, or that of a compliant ally, effectively making the perpetrator the sole prosecutor (Juned et al., 2026). The victim state has very limited legal recourse under UNCLOS to board or prosecute a foreign vessel for damaging a cable outside its own territorial waters.
This enforcement gap has been exploited through ‘grey-zone’ tactics, which are coercive state actions that fall into the ambiguous space between peace and open war (Windward, n.d.). By using ostensibly civilian vessels, such as fishing trawlers or cargo ships, to damage cables, a state can achieve a strategic effect while maintaining plausible deniability. The damage can be attributed to a simple maritime accident, for which UNCLOS provisions were designed. Recent events provide clear examples of this tactic. In 2023, two cables connecting Taiwan’s Matsu Islands were severed by a Chinese-flagged fishing vessel and a cargo ship, an act Taiwan’s authorities described as a form of “gray-zone aggression” (Runde et al., 2024). Similarly, incidents in the Baltic Sea involving damage to cables and pipelines have been linked to Russian and Chinese-owned commercial vessels, but proving deliberate sabotage is notoriously difficult (Matisek et al., 2025). UNCLOS, with its focus on accidental damage and flag-state enforcement, provides an inadequate deterrent against such deliberate, deniable acts of strategic coercion.
Geopolitical Rivalry and the Privatisation of the Seabed
The security of submarine cables has become further complicated by their central role in the geopolitical rivalry between the United States and China, and by a fundamental shift in their ownership. The vast majority of submarine cables are now built, owned, and operated by private sector companies, not governments (TeleGeography, 2026). A small number of firms, including the American company SubCom, France's Alcatel Submarine Networks, and China’s HMN Technologies, dominate the installation market. Furthermore, tech giants like Google, Meta, Amazon, and Microsoft have become the primary investors in new cables, now owning or leasing around half of all undersea bandwidth worldwide (Runde et al., 2024).
This privatisation creates a conflict of interests. Private companies are primarily motivated by commercial efficiency, seeking the most direct and cost-effective routes for their cables. States, however, increasingly view this infrastructure through a national security lens. The US, for instance, has actively worked to block Chinese firms like HMN Technologies from participating in cable projects involving American companies or landing points. A key example is the Southeast Asia-Middle East-Western Europe 6 (SMW6) cable, where US diplomatic pressure and financial incentives led to the contract being awarded to SubCom instead of HMN Technologies, prompting Chinese telecommunication firms to withdraw their investment (Runde et al., 2024). This has led to what some analysts call a ‘bifurcation’ of the internet, with a US-allied network and a separate Chinese-led network emerging as part of its ‘Digital Silk Road’ initiative. This competition fractures the notion of a single, neutral global network, turning privately-owned commercial infrastructure into a battlefield for state-level power struggles. The legal framework of UNCLOS, which presumes a cooperative environment for a shared global common, is not structured to manage a domain where private infrastructure is weaponised for geopolitical ends.
Conclusion
The protection of submarine cables, the physical backbone of the global internet, has become a critical challenge for international law. The foundational legal principles, established in the 1884 Paris Convention and codified in UNCLOS, were designed for a different era and are proving inadequate for the 21st century. The reliance on flag state jurisdiction for enforcement creates a significant loophole that can be exploited by states conducting ‘grey-zone’ warfare, allowing for deniable attacks on critical infrastructure without triggering a military response. Furthermore, the increasing securitisation of cables amid US-China rivalry and the dominance of private tech companies in their ownership and construction adds layers of complexity that the state-centric UNCLOS framework was not designed to handle. This has resulted in a fragmented and contested domain where the rules of the sea are struggling to keep pace with the realities of modern technology and geopolitics. To ensure the security of these vital digital arteries, a more robust governance model is required, one that moves beyond the limitations of UNCLOS and fosters genuine cooperation between states, international bodies, and the private companies that now control the seabed.
References
Convention for the Protection of Submarine Telegraph Cables (Paris Convention) (1884) 14 March 1884.
Juned, M., Yani, Y. M., Nidatya, N., Darmastuti, S., Astuti, W. R. D. and Sadiawati, D. (2026) ‘Contemporary interdependence and the governance gap: the obsolescence of UNCLOS in submarine cable security’, Frontiers in Political Science, 8. [Note: The date is cited as provided in the source material, though it is in the future].
Matisek, J., Langan, J., Rolander, A. M. and Brown, D. A. (2025) Seabed Warfare is Here: A U.S. – Led Global Strategy to Secure the Ocean Floor. Center on Irregular Warfare and Armed Groups Policy Paper No. 1. [Note: The date is cited as provided in the source material, though it is in the future].
Runde, D. F., Murphy, E. L. and Bryja, T. (2024) Safeguarding Subsea Cables: Protecting Cyber Infrastructure amid Great Power Competition. Center for Strategic & International Studies.
TeleGeography (2026) Submarine Cable Frequently Asked Questions. Available at: https://www2.telegeography.com/submarine-cable-faqs-frequently-asked-questions (Accessed 15 October 2023).
United Nations (1982) United Nations Convention on the Law of the Sea. 10 December 1982, 1833 UNTS 3.
United Nations Environment Programme World Conservation Monitoring Centre (UNEP-WCMC) (2009) Submarine Cables and the Oceans: Connecting the World. UNEP-WCMC Biodiversity Series No. 31.
Windward (n.d.) What Is the Maritime Gray Zone? Available at: https://windward.ai/maritime-ai-insights/what-is-maritime-gray-zone/ (Accessed 15 October 2023).
