1. Introduction

Submarine cables and pipelines—serves as the fundamental foundation of worldwide digital connectivity and energy security. The United Nations Convention on the Law of the Sea (UNCLOS) establishes a fundamental regulatory framework that applies equally to both cables and pipelines. Nevertheless, this reflects a notable imbalance in consequences of damage, particularly concerning environmental impact.

Submarine cable damage typically results in disruptions to digital transmission or communication delays, with minimal effect on the natural environment. In comparison, submarine pipelines—particularly those conveying hydrocarbons—pose significant environmental and geopolitical threats. Their rupture, whether resulting from accident, sabotage, or negligence, may contribute to transboundary marine pollution, ecological deterioration, and substantial economic consequences. Nevertheless, UNCLOS does not offer a legally differentiated response tailored to address such disparities of environmental damage.

This discrepancy was prominently evident in September 2022, following the sabotage of the Nord Stream 1 and 2 pipelines in the Baltic Sea (Reuters 2025b).¹⁾ The incident resulted in an unparalleled discharge of methane—estimated between 445,000 and 485,000 tonnes— that not only disturbed the delicate marine ecosystem but also had long-term atmospheric consequences, affecting nearly 14% of the Baltic Sea by exposing areas to methane concentrations five times higher than natural background levels (ESA 2025).²⁾ A further event involving the Balticonnector cable between Finland and Estonia in October 2023 showed even more systemic weaknesses in the security of underwater energy infrastructure (BBC 2023; Council of the European Union 2023).³⁾ The potential environmental disaster posed by pipeline failures, including persistent chemical spills, habitat destruction, and significant greenhouse gas emissions, calls for a more reinforced regulatory approach.

This article argues that the current framework established by UNCLOS does not sufficiently address the specific environmental vulnerabilities associated with Submarine pipelines. The examination of various legal frameworks for the protection of cables and pipelines, as well as for addressing recent acts of sabotage and spills, illustrates that there is an urgent need for a legally sound review that is environmentally sensitive.

2. Overview of Subsea Infrastructure: Strategic and Legal Dimensions

The informatization, globalization, and energy transition of modern society are built upon physical infrastructure. Among these, subsea infrastructure represents the most tangible and essential physical foundation connecting the entire world. ‘Subsea infrastructure’ is a concept that collectively refers to structures or systems installed on the seabed to perform functions such as communications, energy, power, surveillance, and defense. Its importance is increasingly recognized in maritime security and the law of the sea. Generally, subsea infrastructure consists of the following four types: submarine telecommunication cables, oil & gas pipelines, power transmission cables and submarine surveillance or military sensors. These include submarine cables and energy pipelines, which serve as the core infrastructure of the global economy and security systems (Bueger and Liebetrau 2023).

Submarine cables are essential to the global internet infrastructure, connecting every country. Nearly all digital communications, including voice, data, financial signals, and streaming video, are carried by these fiber-optic cables. Submarine cables carry at least 99% of all international communication traffic (ITU 2026). Satellite-based communications are also used, but they are not the main way communication is sent.

There are over 485 major cable networks around the world, with a combined length of more than 1.4 million kilometers. The most concentrated connections are between the U.S. and Europe, the U.S. and Japan, and Southeast Asia and Europe (TeleGeography 2025). These cables are used for a variety of purposes, including private communications, cross-border financial transactions (such as SWIFT), and military transmissions that are classified. Therefore, submarine communication cables are not merely private assets, but rather “dual-use infrastructure” central to national security.

Nevertheless, private telecommunications companies mostly install and operate these cables, and the international community has very limited legal regulation. While the United Nations Convention on the Law of the Sea (UNCLOS) includes provisions concerning submarine cables, it has loopholes and limitations in its substantive protection obligations and liability framework for violations (Lott 2025). Specifically, there are virtually no provisions in place to safeguard against potential military attacks, nor are there any international regulations mandating countermeasures for such attacks. Furthermore, there is an absence of provisions for the maintenance and repair phase following installation.

Submarine energy pipelines refer to transport infrastructure buried underwater to transfer oil or natural gas from offshore oil and gas fields to land, or for export/ import purposes between countries. Energy supply networks between Europe, the Middle East, Russia, and Asia are particularly significantly reliant on pipelines, including energy pipelines, and their strategic importance has recently drawn significant attention (van Soest et al. 2025). For example, Nord Stream I and II were massive high-pressure pipelines over 1,200 km long, transporting natural gas from Russia through the Baltic Sea to Germany. They were critical infrastructure supplying over 45% of the EU’s total gas consumption by 2023 (Nakhle 2025; Russell 2021). However, when the pipeline was destroyed by underwater explosions in September 2022, rendering it effectively permanently unusable, the European energy market experienced severe disruption. This incident was a signal flare for ‘asymmetric hybrid warfare between nations’ (Reuters 2025a).

Another case involves the Balticconnector (Finland–Estonia pipeline). When this pipeline was damaged in 2023, Finland’s Ministry of Defense suggested the possibility that the Chinese cargo ship Newnew Polar Bear intentionally dragged its anchor, causing the damage (The Guardian 2023). This was assessed as a classic example of grey-zone tactics using civilian vessels.

Energy pipelines function not merely as routes for the transport of energy, but rather, they are considered a component of strategic infrastructure that encompasses a variety of factors, including international energy security, climate, and military deterrence. Pipeline damage has the potential to give rise to two principal categories of consequences: first, the disruption of energy supply systems; and second, the risk of hazardous incidents leading to large-scale marine environmental pollution. In the event of such incidents, legal and environmental response systems must be designed to provide significantly more robust protection than that which is typically required for communication cables.

The installation of subsea infrastructure is predominantly focused in maritime regions due to various factors, such as installation costs, geographical characteristics, depth of water and ocean weather conditions. The Strait of Malacca, southern Sri Lanka, the eastern Mediterranean, and the northern Baltic Sea are regions where multiple subsea infrastructures intersect. A military intervention in these regions could provoke an intricate sequence of events, exerting substantial influence on multiple nations.

The ownership and operation of a large amount of this infrastructure is managed by private entities, leading to uncertainty concerning jurisdiction, liability, and compensation criteria in the event of accidents. In the case of damage to submarine cable on the high seas, various stakeholders may be implicated, including the installing nation, the impacted nation, adjacent coastal governments, and the flag state of the vessel. However, international law does not provide sufficiently clear or practically applicable criteria for attributing responsibility in the context of subsea infrastructure damage. This is particularly evident in the case of energy pipelines. Under UNCLOS Article 79, all States are entitled to lay pipelines on the continental shelf, subject to the consent of the coastal State only with respect to the delineation of the pipeline route. However, while general environmental obligations exist under Part XII of the Convention, there remains a lack of detailed and pipeline-specific regulations governing operational safety and environmental protection. This has led to legal difficulties and delayed responses when conflicts happen between nations.

3. Subsea Infrastructure as Emerging Environmental Risk: Implications from Recent Incidents

Nord Stream Pipeline Sabotage (2022)

In September 2022, significant underwater explosions caused damage to the Nord Stream 1 and 2 gas pipelines in the Baltic Sea, resulting in the largest recorded release of methane. Attribution remains contentious, however evidence indicates state-sponsored sabotage (BBC 2022). This incident not only heightened global political sensitivities but also triggered an unparalleled environmental catastrophe. Analytical studies from this incident indicate that the explosion resulted in a methane leak of between 445,000 and 485,000 tonnes, marking it as the highest single-event methane discharge recorded (ESA 2025). The immediate consequence was the rapid introduction of massive amounts of methane into the Baltic Sea, significantly increasing its concent- rations and affecting both marine and atmospheric environ- ment. Data indicated that, in the days following the inci- dent, methane levels in affected areas surpassed normal background values by as much as five times, with a spatial extent spreading across 14% of the Baltic Sea (Mohrmann et al. 2025). These significant environmental consequences of a single pipeline incident highlight the considerable hazards that pipelines pose relative to submarine cables. The Nord Stream Sabotage highlights the need to reevaluate the risks associated with our subsea infrastructure, particularly as these pipelines face less rigorous safety and environmental oversight under current regulatory framework.

Balticconnector Rupture (2023)

In October 2023, the Balticconnector incident, involving the rupture of a gas pipeline and associated communication cables due to anchor dragging, demonstrated how different states attempt to assert jurisdiction in the EEZ. Finland and Estonia conducted a joint investigation, with Finland contending that, given the damage occurred within its EEZ, it held jurisdiction. In contrast, Estonia has characterised the incident as an attack on critical infrastructure, necessitating robust protection measures. This case demonstrates the difficulties involved in reconciling conventional navigation legislation with contemporary hybrid warfare strategies, and in expanding the enforcement capabilities of coastal states beyond the limits of territorial waters (Mohrmann et al. 2025).

Black Sea Pipeline Threats (2023–2024)

Recent statements suggest that Russia attacked under- water infrastructure in the Black Sea, including an under- water gas pipeline linking Ukraine’s Odesa area to mari- time energy terminals (TRT World 2025, Siddiqui 2025). Ukrainian intelligence (HUR) asserts that Russia had previously utilized naval drones and sabotage teams in early 2024 to target this infrastructure within the context of hybrid operations in the vicinity of Snake island and Zmiinyi Island (Rishko 2024). Although the scope of the physical damage remains classified, satel- lite imagery and AIS data confirm a surge in “dark fleet” activity and potential pipeline disruption zones in contested maritime corridors. This incident demonstrates how Submarine pipelines can become geopolitical and environmental flashpoints, particularly in areas where there is no clear legal authority or multilateral emergency response mechanisms.

These cases illustrate the dual vulnerability of submarine pipelines, which function both as strategic targets and under threat of significant environmental damage. The lack of legally codified preventive inspection rights, standardized forensic investigation protocols, and integrated marine environmental monitoring mechanisms renders Submarine pipelines inadequately protected under existing international legal frameworks, despite the potentially significant transboundary environmental and security consequences arising from their disruption.

4. Necessity for Distinct Regulations of Submarine Cables and Pipelines differences in Legal and Environmental Implications

Submarine cables are principally composed of fiber-optic cables facilitating high-speed data transmission across continents. These cables are primarily overseen by private consortia, comprising technology or telecommunications companies. The damage caused by submarine cable does not pose a direct threat to marine ecosystems. In contrast, pipelines are often employed to transport hydrocarbons (such as oil and natural gas) under pressure. These pipelines are operated or co-owned by energy companies with ties to the state. The consequence of a rupture or sabotage of a pipeline may be substantial, with the risk of significant oil spills, fires, or explosions, which can have transboundary effects on marine life, coastal economies, and human health. Despite this functional and environmental distinction, international law lacks the specific environmental provisions or incident-specific emergency protocols to address pipeline-specific threats.

Impact Scale: Ruptured submarine pipelines can cause significant ecological harm, contaminating the surrounding marine environment and increasing atmospheric greenhouse gas concentrations. The Nord Stream disaster exemplifies this risk, featuring catastrophic methane emissions that much surpass the environmental impacts usually triggered by cable damage (UNEP 2023).

The environmental damage resulting from a pipeline incident is everlasting. Chemical spills may remain in marine environments for long periods of time, resulting in irreversible harm to ecosystems and diminishing the resilience of local marine ecosystems. Conversely, the damage caused by cable disruptions usually temporary and may be promptly repaired by technological solutions.

Economic and Social expenses: Damage to subsea cables can disrupt global data flows and result in substantial economic losses; but, the series of consequences of pipeline breakdowns—which range from irreparable ecological harm to disruptions in coastal community livelihoods—are generally more severe. These impacts require not only sufficient coverage and compensation mechanisms but also more stringent preventive regulations.

Insufficient Environmental Protections: Existing environmental impact assessments under UNCLOS insufficiently cover the full spectrum of potential hazards linked to pipeline developments. The possibility of uncommon yet consequential events is often greatly underestimated. This results in a regulatory framework that is inadequately prepared to deal with the impacts of catastrophic failures, as demonstrated by the Nord Stream incident.

Table 1 illustrates that submarine telecommunications cables feature relatively rapid repair cycles and significant systemic redundancy, allowing prompt recovery even during partial outages. On the other hand, subsea oil and gas pipelines demonstrate considerable redundancy constraints, resulting in potential prolonged disruptions and significant impact on the environment. Table 2 further describes the economic consequences of such incidents, with gas pipeline outages alone resulting in estimated losses of €20 billion during extended occurrences.

5. Structural Regulatory Gaps in Existing Legal Frameworks

Historical Cable focusing regulation

The initial international framework can be traced back to the International Convention for the Protection of Submarine Telegraph Cables, commonly known as the Paris Convention (1884). Concluded in Paris on March 14, 1884, and entering into force on May 1, 1888, the Convention established an obligation for its 36 States Parties to protect submarine cables laid on the ocean floor as well as those that landed in coastal territories. Key provisions defined the geographical scope of the Convention and imposed punitive measures for willful or negligent cable damage. Although the Paris Convention focused exclusively on cables on the high seas, negotiators presumed that coastal states would impose complementary domestic regulations for cables within their territorial boundaries.

Article I stipulates that the Paris Convention is applicable “outside territorial waters to all legally established submarine cables that are landed on the territories, colonies, or possessions of one or more of the High Contracting Parties.” Consequently, the Paris Convention safeguards certain submarine cables located on the seabed of the high seas. This Convention comprises three fundamental provisions (NOAA 2023). Article II⁴⁾ stipulates that it is a serious infraction to willfully or by culpable negligently damage a submarine cable in a manner that may disrupt telegraphic communications, either wholly or partially. Article IV⁵⁾ provides that the owner of a cable who, while laying or repairing their own cable, breaks or injures another cable, is responsible for the expenses of repairing of the damage, without detriment to the provisions of Article II of the Convention. Article VII stipulates that owners of ships or vessels who can prove that they have sacrificed an anchor, a net, or other fishing gear to prevent damage to a submarine cable shall be compensated by the cable’s owner. When the officers of a warship or a ship designated by a Party to the Paris Convention suspect that another vessel has violated the Convention’s measures, they may require the captain or master of that vessel to exhibit the official documents verifying the nationality of said vessel and prepare a report to be sent to the vessel’s flag state for appropriate action, regardless of the nationality of said vessel.

Nonetheless, the convention governs solely submarine cables, excluding pipelines. The Paris Convention was established to protect communication cables; but it did not include other submarine infrastructure, such as energy pipelines, within its legal structure. Prior to the ILC’s work on the law of the sea, pipelines were not regulated by dedicated treaties. In 1950, the ILC stated that the freedom to lay submarine cables should also apply to pipelines. Some have suggested that the ILC coupled cables and pipelines because it viewed both as means of communication (ILA 2020). Subsequently, regulations concerning submarine infrastructure were expanded under the United Nations Convention on the Law of the Sea (UNCLOS). However, the tradition of focusing on telecommunications persisted, resulting in pipelines receiving only relatively limited regulations. The initial disposition towards telecommunications during the early convention shaped the UNCLOS legal framework and is a contributing factor to the current insufficiency of full coverage for pipeline security and environmental threats.

During the late 1950s, the legal regime governing the high seas was further expanded at the United Nations Conference on the Law of the Sea in Geneva. Several conventions, including the Geneva Convention on the High Seas (HSC) and the Geneva Convention on the Continental Shelf (CSC), were adopted. The HSC reasserted the right of all states to lay submarine cables—extending protection not only to telegraph cables but also to telephonic and even high-voltage power cables—thereby confirming the concept of freedom of the high seas. In parallel, the CSC addressed the rights and limitations on the exploitation of the continental shelf while ensuring that cables laid on the seabed were not unduly obstructed by coastal state measures.

The 1958 Geneva Convention on the High Seas (HSC) established the first comprehensive international legal framework governing submarine infrastructure on the high seas. Article 2 of the HSC explicitly declares the freedom of the high seas, stipulating that “the high seas are open to all States and no State may claim sovereignty over any part thereof.” This freedom of the high seas includes the “freedom to lay submarine cables and pipelines,” guaranteed equally to both coastal and non-coastal states (Article 2, para. 3).

These freedoms are further detailed in Article 26 and subsequent provisions. Article 26 specifies that all States have the right to lay cables and pipelines on the seabed of the high seas, provided they do not impair the repairability of existing facilities of other States. It also clarifies that coastal States may not interfere with the laying or maintenance of cables or pipelines, except when taking reasonable measures for the exploitation of continental shelf resources.⁶⁾

Article 27 requires each State to adopt legislative measures to punish its ships or nationals who intentionally or through gross negligence damage submarine cables or pipelines on the high seas. This provision specifically includes not only telecommunication networks but also high-voltage power cables within the scope of protection.⁷⁾

Article 28 establishes the civil liability principle that the party causing damage to existing facilities during the laying or repair of submarine cables or pipelines must bear the repair costs.⁸⁾ The subsequent Article 29 ensures that if fishing vessels, etc., abandon nets or anchors to avoid cables or pipelines, they can receive compensation from the facility owner if the damage resulted from reasonable precautionary measures.⁹⁾

In short, HCS comprehensively regulated the installation and protection obligations, responsibilities, and compensation systems for submarine infrastructure based on the freedom of the high seas, thereby serving as the precursor to the United Nations Convention on the Law of the Sea (UNCLOS). By explicitly including not only cables but also pipelines and high-voltage power lines, it formed the legal foundation for the regulation of modern marine infrastructure.

The coastal State may not impede the laying or maintenance of submarine cables or pipelines on the continental shelf by other States. Subject to its right to take reasonable measures for the exploration of the shelf and the exploitation of its natural resources, the coastal State may establish conditions for cables or pipelines entering its territory or territorial sea.¹⁰⁾

Installation Rights versus Environmental Protection under UNCLOS

1982 United Nations Convention on the Law of the Sea (UNCLOS) provides the general legal framework governing the installation, maintenance, and protection of submarine infrastructure. Ratified by 168 countries globally, UNCLOS is often described as the ‘constitution of the oceans’ and sets out the rights for installation and operation of both submarine cables and pipelines. UNCLOS incorporates provisions that recognize the freedom to lay submarine cables and pipelines, even while permitting coastal states to regulate these activities within their jurisdiction—particularly in the territorial sea and along the continental shelf. UNCLOS delineates both the rights and responsibilities of coastal and flag states with respect to activities within different maritime zones, including territorial seas, exclusive economic zones (EEZs), and the continental shelf. Submarine cables and pipelines addressed in 10 articles of the UNCLOS provisions.¹¹⁾ These provisions may be analytically grouped into two broad categories: (i) rights and responsibilities of States in different maritime zones, and (ii) rules concerning the protection of submarine infrastructure.

The UNCLOS includes provisions that protect the rights to install submarine cables and pipelines while allowing coastal states to control these activities within their jurisdiction. Rather than establishing uniform regulations, the Convention strikes a balance between the freedom of installation and coastal state authority across different maritime zones.

The Freedom to install submarine cables and pipelines

UNCLOS ensures the rights of all States to install submarine cables and pipelines on the high seas. Under Article 87.1(c), the laying of submarine cables and pipelines is recognized as one of the freedoms of the high seas. Article 112.1¹²⁾, all States are entitled to lay submarine cables and pipelines on the bed of the high seas beyond the continental shelf.

Exclusive Economic Zone (EEZ), extending 200 nautical miles from a Coastal state’s baseline, confers upon States’ sovereign rights to explore, exploit, conserve the natural resources, as set out in Article 56.1. At the same time, Article 58.1 guarantees that all States have the freedom to install submarine cables and pipelines in the Exclusive Economic Zone (EEZ), while allowing the Coastal State to implement “reasonable measures” for resource exploration. Article 58.1 provides that all States, whether Coastal States or land-locked, enjoy, subject to the relevant provisions of this Convention, the freedoms referred to in Article 87 of navigation and overflight and of the laying of submarine cables and pipelines. These freedoms are to be exercised with due regard to the rights and duties of the coastal State, in accordance with Article 58(3). In this respect, submarine cables and pipelines are distinct from other activities conducted in the EEZ, such as fishing, seabed mining, and the production of energy from the water and winds, which fall within the sovereign rights of the coastal State under Article 56.1. By contrast, the laying of submarine cables and pipelines is treated as a high seas freedom applicable within the EEZ, subject to the due regard obligation.

Coastal State jurisdiction and regulatory constraints

Notwithstanding the freedoms recognized under UNCLOS Coastal States are granted varying degrees of regulatory authority across different maritime zones. The territorial sea is defined as the zone extending 12 nautical miles from a coastal state’s baselines, wherein the coastal state exercises complete sovereignty. Within this zone, the coastal states may adopt laws and regulations aimed at protecting submarine cables and pipelines, which includes regulating vessel activities likely to cause damage.

The installation and repair of submarine cables do not constitute an exercise of the right of innocent passage under Article 19(2), as such activities are not directly related to navigation. Accordingly, Article 21.1 allows the Coastal State to adopt laws and regulations, in conformity with the provisions of this Convention and other rules of international law, relating to innocent passage through the territorial sea, in respect of the protection of cables and pipelines.¹³⁾

In archipelagic waters, UNCLOS provides a distinct regime. According to UNCLOS article 51.2, all States are entitled to maintain existing submarine cables passing through the waters of an archipelagic state without making landfall. An archipelagic State shall permit the maintenance and replacement of such cables upon receiving due notice of their location and the intention to repair or replace them. This provision reflects a balance between the functional integrity of existing submarine infrastructure and the territorial sovereignty of the archipelagic State. However, this freedom does not guaranteed unconditionally to all submarine cable activities. Archipelagic states may require consent for and impose conditions on new submarine cables that are not replacements and cables making landfall.

With respect to the continental shelf, Article 79 affirms the right of all States to lay submarine cables and pipelines, subject to the consent of the coastal State only with regard to the delineation of the pipeline route. Article 78.2 affirms that “the exercise of the rights of the coastal State over the continental shelf must not infringe or result in any unjustifiable interference with the rights and freedoms of other States. This indicates a legal framework in which the laying and maintenance of submarine cables and pipelines is guaranteed under international law, but subject to coordination with the rights of the coastal State.

‘Due Regard’ standard and structural ambiguity

States are required to exercise their freedoms with due regard for the interests of other States, as stated in Article 87.2. This standard is further specified in the context of submarine infrastructure. In particular, Article 79.5 provides that, when laying submarine cables and pipelines on the continental shelf, States shall have due regard to cables and pipelines already in position and must not prejudice the possibilities of repairing existing infrastructure.

Within the EEZ, the obligation of due regard applies in both directions: coastal States, in exercising their sovereign rights, must have due regard to the rights and duties of other States under Article 56(2), while other States, in exercising freedoms such as the laying of submarine cables and pipelines, have due regard to the rights and duties of the coastal State under Article 58(3). The same standard of ‘due regard’¹⁴⁾ that applies to the high seas (Article 87.2) and the continental shelf (Article 79.5) is therefore extended to activities involving submarine cables and pipelines in the EEZ, ensuring a balance between navigational freedoms and interests of coastal States.

Coastal States possess sovereign rights over the continental shelf for the purpose of exploring and exploiting its natural resources. At the same time, Article 79(1) of UNCLOS affirms the right of all States to lay submarine cables and pipelines on the continental shelf, in accordance with the provisions of that article. However, under Article 79.5¹⁵⁾, States laying such infrastructure are required to exercise due regard to cables and pipelines already in position, including the need not to prejudice their repair. Conversely, Article 78.2 provides that the exercise of the coastal State’s rights over the continental shelf must not result in unjustifiable interference with the rights and freedoms of other States. In this context, States are also required to observe an obligations of ‘due regard’ to existing infrastructure, as Article 79.5 emphasizes. The obligation of due regard must be reconciled with the coastal State’s sovereign rights over the continental shelf.

Pipelines versus Cables: Differentiated consent and control, environmental concerns

Article 79.2 provides that the Coastal State must not impede the laying or maintenance of submarine cables or pipelines, except where necessary for “the exploration of the continental shelf,” “the exploitation of its natural resources,” or the “reduction and control of pollution from pipelines,” but notably not from cables. This raises interpretive questions as to whether the Coastal State may exclude submarine cables from seabed areas due to energy or mineral exploration or exploitation, or on the basis of environmental protection concerns.

The Convention further distinguishes between pipelines and cables regarding route control. Article 79.3 provides that “the delineation of the course for the laying of such pipelines (but not cables) on the continental shelf is subject to the consent of the coastal State.” In contrast, cables may be laid without requiring prior consent for routing, though still subject to general due regard obligations.

Article 79.4 confirms that “nothing in this Part affects the coastal State’s jurisdiction over cables and pipelines constructed or used in connection with the exploration of its continental shelf or exploitation of its resources or the operations of artificial islands, installations and structures under its jurisdiction.” This includes submarine telecommunications and power transmission cables and pipelines connecting offshore wind farms, marine hydrokinetic facilities, and oil and gas platforms.

Regarding the Area, cables and pipelines that do not involve the transport of seabed resources from the Area are not considered “activities in the Area” subject to the jurisdiction of the International Seabed Authority (ISA), as defined under Part XI of the Convention.¹⁶⁾ Article 147.1 provides that “activities in the Area shall be carried out with reasonable regard for other activities in the marine environment,” while Article 147.3 establishes the reciprocal obligation.

Limitations of Submarine Cables and Pipelines Protection under UNCLOS

Articles 113 to 115 of UNCLOS largely update the 1884 International Convention for the Protection of Submarine Telegraph Cables by broadening legal safeguards to encompass pipelines and high-voltage power cables. Nonetheless, the extent and enforceability of these prohibitions are constrained. Articles 113 and 114 specifically pertain to damage occurring beneath the high seas’, excluding other maritime zones such as the Exclusive Economic Zone, continental shelf, or archipelagic waters, where cable networks are similarly existent and vulnerable.

Article 113¹⁷⁾ requires States to adopt national laws and regulatios ensuring that the wilful or culpably negligent damage of submarine cables and pipelines, which may disrupt telegraphic or telephonic communications, including high-voltage power cables. Nevertheless, the provision primarily has a reactive character— emphasizing retributive measures after an injury rather than proactively implementing preventive or protective measures. Furthermore, its effectiveness is wholly dependent upon domestic implementation, which significantly differs among States and poses challenges for monitoring or enforcement in practice. Article 114¹⁸⁾ further requires States to establish a liability for damages in the course of laying or repairing a submarine cable or pipeline, cause damage to another cable or pipeline, thereby obliging the responsible party to bear the cost of repairs. This provision assumes a definitive assignment of liability and an efficient legal framework to uphold cross-border claims, both of which are frequently absent in practice.¹⁹⁾ Article 115²⁰⁾, which specifies reimbursement for shipowners who surrender equipment to prevent damage to cables or pipelines, is equitable in sense but is narrowly defined and challenging to implement, particularly in the lack of proof or transparent reporting procedures.

While UNCLOS Article 79.5 emphasizes the notion of “due regard” for existing submarine infrastructure, this broad criterion provides little operational clarity or enforceability. The Convention lacks to provide technological standards, compulsory notification protocols, or zone safeguards that would significantly mitigate danger in highly populated or abundant in resources seabed regions.

As a whole, these regulations illustrate a fragmented and responsive legal framework, wherein essential obligations are limited to the high seas and reliant upon national legislation. The lack of uniform enforcement methods, preventive measures, and clarity about jurisdictional overlaps undermines the effectiveness of UNCLOS in providing adequate protection for submarine cables and pipelines in the growing congested maritime environment. Submarine pipelines, particularly those that connect directly to a coastal state’s territory or continental shelf, enjoy broader regulatory protections.

Article 79.4 confers coastal states exclusive authority over pipelines linked to their territory, permitting them to adopt domestic legislation for environmental protection and safety (Hartmann and Lott 2025). Furthermore, UNCLOS Part XII, addressing the protection and preservation of the marine environment, imposes specific obligations on states to prevent, reduce, and control pollution deriving from various maritime activities, including potential spills from pipeline damage. In contrast, submarine cables are primarily governed by provisions that emphasize the freedom to install and maintain them without excessive governmental interference (UNCLOS Articles 58.1 and 79.1). Although damage to cables constitutes a violation under Article 113, the environmental and pollution risks linked with cable damage are often less severe than those posed by pipelines. The regulatory framework for cables thus focuses more on protecting commercial communication networks rather than controlling the risk of environmental harm.

6. Structural Fragmentation of Environmental Protection and Regulation caused by Submarine Pipelines

UNCLOS Part XII: Protection of Marine Environment

Subsea pipelines are noted under Article 79 of UNCLOS, which recognizes the right of all states to lay pipelines on the continental shelf of another state, subject to the latter’s consent for route determination. Article 79.4 specifies that the coastal state may not impede the laying or maintenance of such pipelines unless they interfere with resource exploitation. Nonetheless, UNCLOS exhibits a notable regulatory deficit, as it fails to incorporate specific provisions for environmental emergency responses, designated safety zones, or rigorous inspection regimes tailored to the unique risks of submarine pipelines.

The obligations of preventing, reducing and controlling marine pollution marine pollution and protection and preservation of marine environment related to such infrastructure fall under Part XII of UNCLOS in particular Articles 192-196. UNCLOS Articles 192–196 impose obligation on states to protect and preserve the marine environment. Article 192²¹⁾ establishes a general obligation to protect and preserve the marine environment. Article 194.1²²⁾ mandates that states take “all measures necessary to prevent, reduce and control pollution of the marine environment,” including pollution from pipelines. Furthermore, Article 194.2 state that States ensure activities under their jurisdiction or control do not cause pollution damage to other States or beyond areas where they exercise sovereign rights. UNCLOS Article 194.3 mandates that States must address all sources of marine pollution in the exercise of their obligations to protect and preserve the marine environment. The provision explicitly states that the measures taken “shall include, inter alia, those designed to minimize to the fullest possible extent” pollution from various sources, such as: “the release of toxic, harmful or noxious substances, especially those which are persistent, from land-based sources, from or through the atmosphere or by dumping; pollution from vessels; pollution from installations and devices used in the exploration or exploitation of the natural resources of the seabed and subsoil; and pollution from other installations and devices operating in the marine environment.” Article 206²³⁾ requires states to assess the potential effects of planned activities that may cause significant marine environmental harm.

However, these environmental provisions remain decoupled from the pipeline-specific rules under Article 79, resulting in a fragmented regulatory regime. While Articles 192 through 196 stipulate a general obligation to protect and preserve the marine environment, they lack explicit enforcement mechanisms or defined applicable legal thresholds that would effectively address incidents of underwater sabotage.

Regional Seas Conventions

There are several regional seas conventions also provide important environmental norms applicable to subsea pipelines. The 1992 Helsinki Convention on the Protection of the Marine Environment of the Baltic Sea Area (HELCOM) includes specific provisions on pollution prevention, ecosystem protection, and environmental cooperation. Articles 3 and 15 oblige states to avoid activities that could cause long-term degradation of the Baltic ecosystem. Article 7 and Annex VI specify the obligation to provide prior notification and consultation before pipeline installation and the obligation to share information with neighboring states in the event of an accident.

The Bucharest Convention on the Protection of the Black Sea Against Pollution (1992), referred to as the Black Sea Convention, serves as the principal regional legal framework for marine environmental protection in the Black Sea. Article V mandates contracting parties to implement all necessary steps to prevent, mitigate, or regulate pollution originating from offshore installations, implicitly include underwater pipes. Furthermore, the draft Protocol of the Convention on Environmental Impact Assessment (EIA) reflects the framework of the Espoo Convention by mandating prior notification, consultation, and the execution of transboundary EIAs for potentially detrimental infrastructure projects. The Convention includes duties concerning the management of hazardous substances, coordination of emergency responses, and sharing of scientific data (Arts. XIII and XVII). While these steps establish a regional environmental framework, the absence of binding enforcement mechanisms and the protocol’s draft state undermine its effectiveness. Consequently, the Bucharest Convention provides a significant yet insufficient legal framework for mitigating environmental hazards linked to underwater pipelines in the Black Sea area.

This Convention concretizes the pollution prevention obligations under Articles 192–194 of UNCLOS and makes a substantial contribution to preventing disputes related to submarine infrastructure. In 2004, the IMO designated the Baltic Sea as a Particularly Sensitive Sea Area (PSSA), which under Article 194.5 of UNCLOS permits stricter protective measures in such areas (Lott 2011). However, while these treaties offer strong substantive environmental goals, they lack binding procedural enforcement mechanisms, such as sanctions or mandatory inspections.

Espoo Convention and the EIA Gap

The 1991 Espoo Convention on Environmental Impact Assessment in a Transboundary Context is the most advanced convention regulating EIAs for projects such as submarine pipelines. It requires states to inform and confer with potentially impacted nations when a project may result in significant adverse environmental impacts.

Regarding the Nord Stream pipeline, Russia, while merely a signatory and not a party to the Espoo Convention, voluntarily consented to adhere to the Convention’s provisions. However, the required Environmental Impact Assessment procedure neglected to consider significant concerns, including the existence of chemical weapons, the potential for methane leaks, and the disruption of marine ecosystems. The European Parliament and Baltic States condemned the EIA for neglecting to investigate terrestrial route alternatives, according to Espoo’s stipulation in Appendix II(b) to assess “reasonable alternatives.”

In accordance with the precautionary principle, States are required to carry out Environmental Impact Assessments (EIAs) “at an early stage and prior to decision- making” when activities pose a potential risk of substantial environmental harm, even in the absence of definitive scientific evidence linking proposed actions to environmental damage. This is particularly important for submarine pipelines, where preventative legal precautions must be implemented. Article 206 of UNCLOS requires Environmental Impact Assessments (EIAs) where activities under a state’s jurisdiction or control “may cause substantial pollution or significant and harmful changes to the marine environment,” although the clause faces extensive criticism for its insufficient procedural clarity and lack of enforceable duties. The 1991 Convention on Environmental Impact Assessment in a Transboundary Context (Espoo Convention) is crucial in implementing EIA responsibilities for transnational projects such as Nord Stream (Lagoni 2011).

The Espoo Convention addresses significant deficiencies in both UNCLOS and the 1992 Helsinki Convention, as neither provides adequate procedural stipulations for executing transboundary Environmental Impact Assessments (EIAs). Article 206 of UNCLOS, for example, does not specify the precise actions to be undertaken following the completion of an assessment, other than mandating the dissemination of the report as stipulated in Article 205. Article 194.1 imposes an extensive obligation on States to implement all necessary steps to prevent, reduce, and control pollution, thereby implying a duty to act on adverse EIA findings. The International Court of Justice, in its Pulp Mills case, confirmed that Environmental Impact Assessment responsibilities under customary international law are not mere formalities but must be executed with due diligence and at the proper stage of planning (ICJ 2010, para 205). Consequently, in areas where UNCLOS is ambiguous, the Espoo Convention acts as an essential supplementary tool, guaranteeing that States adhere to their environmental responsibilities as outlined in Part XII of the Law of the Sea Convention.

Reflecting ILA framework and enhancing environmental responsibility

The International Law Association’s 2024 Third Interim Report on Submarine Cables and Pipelines emphasizes the interpretive limitations of the exiting UNCLOS Part XII and underscores the need for a new legal framework balancing the protection of submarine infrastructure with the conservation of the marine environment.

According to ILA Report (3^rd; ILA, 2024), pursuant to the United Nations Convention on the Law of the Sea (UNCLOS), all State parties have legal obligations to protect and preserve the marine environment, as articulated in Articles 192 and 194(ILA 2024). These provisions are applicable regardless of the maritime zone in which the environmentally harmful activity occurs, including areas beyond national jurisdiction. Notably, these obligations extend not only to conduct of States but also to activities carried out by private or non-state entities under their jurisdiction or control.²⁴⁾

Damage to submarine infrastructure—whether intentional or negligent, may constitute marine pollution as defined in Article 1.1.4 of UNCLOS. For example, the use of underwater explosives or physical sabotage causing ruptures in gas pipelines results, or is likely to result in deleterious effects, such as the leakage of hydrocarbons or methane, as seen in the 2022 Nord Stream incident. Once such damage constitutes marine pollution under UNCLOS, it triggers the legal responsibility of States. In this regard, States are required to demonstrate due diligence, necessitating the implementation and enforcement of robust regulatory and administrative frameworks to mitigate environmental risks (ILA 2020).

UNCLOS Article 235 reinforces this duty by stipulating that States are internationally responsible for fulfilling their environmental protection obligations and shall be liable under international law when failing to do so. Consequently, a State that causes, enables, or fails to prevent infrastructure damage resulting in pollution may be in breach of UNCLOS Articles 192, 194, and 235 (ILA 2020).

Moreover, because obligations to protect and preserve the marine environment in areas beyond national jurisdiction have been characterized as obligations erga omnes partes, any State Party may invoke the responsibility of a State that breaches them.²⁵⁾ This is particularly significant in cases where no individual State is directly harmed but where collective interests are at stake—such as the conservation of the marine ecosystem of the high seas or “the Area.”²⁶⁾

When environmental harm from subsea infrastructure affects a coastal State, that State may also assert a claim as a specially affected State, under Article 42(b)(i) of the Articles on Responsibility of States for Internationally Wrongful Acts (ARSIWA).²⁷⁾ This could apply, for instance, when transboundary pollution from a damaged pipeline reaches the Exclusive Economic Zone (EEZ) or territorial sea of a nearby coastal State. In light of these legal obligations, intentional acts of sabotage against subsea pipelines and cables are not only matters of national or regional security, but also issues of international environmental law, potentially engaging the legal responsibility of multiple actors.

7. Conclusion: Toward Environmentally Differentiated Legal Approaches for Subsea Pipelines

The urgent need for a regulatory paradigm shift in the control of submarine infrastructure has become increasingly obvious. The higher threat levels of submarine pipelines, in contrast with telecommunications cables, require a distinct legal framework at both international and national levels. These reforms are crucial to enhancing environmental protection and for ensuring the resilience and sustainability of vital marine infrastructure within a complex and interconnected global network.

From a normative perspective, a starting point would be to modify or augment UNCLOS so as to draw a clearer distinction between different categories of underwater infrastructure. This would require the creation of separate regulatory sub-regimes for pipelines and for cables together with tailored standards for environmental impact assessments (EIAs) and incident-response procedures. Although both technologies are subject to baseline assessments prior to installation, pipelines need more stringent and recurrent risk evaluation considering their potential to cause catastrophic leaks and sustained methane emissions.

Due to the structural and operational distinctions, it is essential to implement a legal framework that accommodates varied approaches to underwater cables and pipelines. This system should encompass advanced risk modeling, sector-specific Environmental Impact Assessments (EIAs), rigorous operational and monitoring methods, and clearly defined liability and insurance responsibilities. Regulatory frameworks must encompass the utilization of empirical data and scenario-based models to precisely assess failure rates and environmental impacts, particularly for pipeline projects. These improved EIAs should evaluate worst-case scenarios, including significant chemical releases and ongoing habitat deterioration thus guiding more stringent routing criteria, advanced monitoring systems, and comprehensive emergency preparation.

In addition to preliminary evaluations, the protocols for ongoing surveillance of pipelines must be reinforced. Innovative technologies—such as distributed sensor networks, autonomous underwater vehicles (AUVs), and real-time data analytics—can deliver early-warning indicators and facilitate accelerated responses, thereby reducing prolonged ecological consequences. Given the unequal environmental and economic repercussions of pipeline failures, the liability framework must be adjusted to mandate increased environmental insurance for pipeline operators. These financial commitments would function as incentives for proactive risk management and preventive measures.