Attacks against Europe’s Offshore Infrastructure within and beyond the Territorial Sea under Jus ad Bellum

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The EU and NATO Member States appear to be engaged in a shadow war with Russia where pipelines, cables, and windfarms connected with the former are allegedly targeted by the latter. The recent suspected sabotage against a 77-km-long submarine gas pipeline and a telecommunications cable linking Estonia and Finland fuels the common fear among European States of Russian sabotage against Europe’s offshore critical infrastructure. This post addresses the question of how sabotage impacts the safety of objects of critical offshore infrastructure and how to increase their legal resilience. The post focuses on incidents that have occurred in the exclusive economic zone (EEZ) of States, including the Nord Stream explosions of last year (for an earlier EJIL: Talk! post on this see here) and the damaging of the submarine gas pipeline and cable of the NATO Member States Estonia and Finland.

After briefly discussing the reactions of States to these incidents, the post addresses the threshold subject of whether suspected acts of sabotage against critical offshore infrastructure can be considered as an “armed attack” which could give rise to action taken in self-defence. The post then considers against which State such an armed attack can be regarded as having been committed, and in particular, whether the coastal State can be regarded as the victim of the attack. This last question is important because the coastal State does not possess territorial sovereignty over the EEZ, nor does that State necessarily have jurisdiction over or indeed a link to all infrastructure located there. Finally, the post underlines the significance of safety zones for the protection of offshore critical infrastructure. 


Acts of sabotage against submarine pipelines and cables in Europe from 2021 to 2023

In April 2021, a fiber-optic cable connecting the Norwegian Svalbard archipelago and the mainland of northern Norway was cut, and a long section of the cable was removed (see here). The Norwegian authorities found the lost section of the cable at the end of 2021 lying on the seafloor of the Norwegian EEZ many kilometers away from its original location (see here). In January 2022, another cable connecting the mainland coast of Norway with Svalbard was damaged (see here).

On 19 October 2022, at least three fiber-optic cables that reportedly connected Marseille to Lyon, Milan, and Barcelona were cut off the French coast (see here). The following morning, a cable connecting the British Shetland Islands to the rest of the United Kingdom’s (UK) communications system was cut in two sections – as a result of which, the Shetland Islands briefly lost telephone and Internet services (see here). A Russian research ship was spotted near the cables when they were cut supposedly due to a fishing trawler’s activity in the area (see here). A couple of weeks before that incident, a cable connecting the Shetland Islands and the Danish Faroe Islands was broken (see here).

In September 2022, explosions partly destroyed the Nord Stream pipelines in the Danish and Swedish EEZs (see here). The Swedish investigators have characterized these explosions as an act of sabotage (see here). A year later, in October 2023, a potential act of sabotage resulted in a partial destruction of a concrete-coated submarine gas pipeline (jointly owned by Estonian and Finnish companies) in the Finnish part of the EEZ corridor in the Viro Strait that is located between Estonia and Finland in the Gulf of Finland. In addition, in the Estonian part of the narrow EEZ corridor, a telecommunications cable linking the two States had been cut.

The President of Finland, Mr. Sauli Niinistö commented that: “It is likely that the damage to both the gas pipeline and the communication cable is the result of external activity.” The Russian merchant ship SVG Flot was spotted spending three days, including the day when the cable and the pipeline were damaged, in the relevant maritime area. The Secretary General of NATO, Mr. Jens Stoltenberg, made it clear that if the incidents were “proven to be an attack on NATO critical infrastructure … it will be met by a united and determined response from NATO”. A few days later, UK Prime Minister Mr. Rishi Sunak announced that, in 2024, the UK will deploy over 20,000 soldiers to northern Europe (16,000 soldiers to Norway and Estonia alone) complemented with eight Royal Navy ships, 25 fighter jets and an aviation task force to deter hybrid activities and protect critical infrastructure in the region.


Implications of the Nord Stream Explosions for the Protection of Critical Offshore Infrastructure under Jus ad Bellum

The response of the Danish Prime Minister to the Nord Stream explosions illustrates the importance of legal resilience of critical infrastructure located in EEZ against the unlawful use of force. The Danish Prime Minister made it clear that the attacks against the Nord Stream pipelines were not attacks against Denmark – as the explosions of the pipelines occurred in international waters and not in the Danish territorial sea.

The Nord Stream explosion sites were close to the outer limits of the Danish and Swedish territorial sea and next to major shipping routes. If these acts of sabotage had occurred in the territorial sea of Germany, Denmark, or the Russian Federation, they would have likely amounted to an armed attack, thus triggering the right of self-defence under Article 51 of the United Nations Charter. The Secretary General of NATO, Mr. Jens Stoltenberg, commented in the aftermath of the Nord Stream explosions that an attack on critical offshore infrastructure can trigger collective self-defence under Article 5 of the North Atlantic Treaty.


Does a Use of Force against Critical Offshore Infrastructure Amount to an Armed Attack also beyond the Limits of the Territorial Sea?

It follows first and foremost from the ‘scale and effects’ test of the Oil Platforms Case (paras 51-64) that if the unlawful use of force in an EEZ or on the continental shelf against underwater tunnels, windfarms, cables, pipelines, platforms, or other objects of critical infrastructure causes significant damage and especially where the unlawful use of force results in the loss of human life, the State that is attacked can invoke the right of self-defence under Article 51 of the UN Charter. However, for that right to be lawfully invoked, it must be the case that the incident was a deliberate attack and not a mere accident (see Oil Platforms Case at para 51).

In the view of the present author, sabotage against critical offshore infrastructure outside the sovereign territory of a coastal State can potentially also amount to an armed attack, thus triggering the right of self-defence under Article 51 of the UN Charter. For example, it is doubtful that Denmark would continue to draw a line between an armed attack and less grave uses of force on the basis of the outer limits of its territorial sea if explosions targeted, for example, the German-Danish immersed tunnel in the EEZ corridor of the Femern Strait (Fehmarnbelt) that was established under the German law (at section 1) and Danish law (at section 6(2)). Unlike many other submarine tunnels that are tunneled through the continental shelf, the Femern Strait’s road and rail tunnel is constructed on the seabed by laying premade concrete sections of the tunnel to a trench on the seabed. Notably, the tunnel to the extent that it is located outside the territorial sea of the coastal State does not form part of the coastal State’s territory.

Similar to attacks against tunnels, cables, or pipelines, the unlawful use of force against offshore windfarms in a coastal State’s EEZ at least has the potential to amount to an armed attack under Article 51 of the UN Charter if it causes significant damage to the coastal State, especially if it leads to massive power outages in the coastal State’s population. It is common for offshore windfarms to be located in a coastal State’s EEZ. If numerous explosions would target, for example, the Danish windfarms that are located next to Bornholm Island and in the vicinity of where the Nord Stream explosions occurred, would it be likely that Denmark would still claim that it does not consider such use of force to amount to an attack against Denmark as the explosions occurred in international waters?


Which State May Invoke the Right of Self-Defence in Response to Attacks against Offshore Infrastructure?

The Nord Stream explosions have illustrated that claiming another State’s responsibility for an intentionally clandestine use of force (sabotage) in the marine environment which is suitable for concealing any evidence about the origin of the attack, is not an easy task for the victim State that needs to bear the burden of proof. The classification of the use of force as an armed attack under Article 51 of the UN Charter depends inter alia on the perpetrator of the operation, the distinction being made mostly on the basis of whether the perpetrator is a State organ or a non-State actor (see, e.g., Nicaragua v. the United States, para 195). The International Court of Justice (ICJ) has clearly made this distinction by limiting the right of self-defence to attacks conducted by one State against another State (at para 139). Notably, State practice (e.g., the response by the United States and its allies to the acts of terror of 11 September 2001) demonstrates more flexibility in categorizing attacks by non-State actors as an armed attack.

In addition, the coastal State needs to establish a direct link with the targeted infrastructure so that the attack against the infrastructure can be equated with an attack on that State (see Oil Platforms Case at para 64). Establishing a direct link with the targeted infrastructure is complicated if the location of attack against the critical infrastructure falls outside the limits of the coastal State’s territorial sea since offshore infrastructure is not subject to flag State jurisdiction (unlike ships). Article 60(2) of UNCLOS stipulates that the coastal State has exclusive jurisdiction over installations and structures in its EEZ, whereas the coastal State’s jurisdiction is more narrowly construed under UNCLOS in respect of submarine cables and pipelines (Art 79(2) and (4)).

In an EEZ and on the continental shelf, third States have the freedom to lay submarine cables and pipelines (Articles 58(1), 79(1), and 87(1)(c) of UNCLOS). Hence, as the targeted cables or pipelines in the coastal State’s EEZ or continental shelf “might have no connection with the coastal State” (Kaye at 418), the unlawful use of force against these objects does not prima facie breach the coastal State’s sovereign interests.

It would be possible to establish a direct link with the targeted underwater pipeline or cable if the destruction caused significant damage to the population of the coastal State (e.g., substantial loss of human life, significant disruption of critical services such as internet connection or electrical grid). In addition, as suggested by Azaria and Ulfstein, arguably another relevant factor for determining whether a particular State is entitled to invoke the right of self-defence might be the incorporation of the company that owns the targeted submarine pipeline or cable in the State claiming self-defence.

Unlike the Nord Stream pipelines, the damaged Estonian-Finnish gas pipeline and submarine cable are owned by the companies incorporated in the coastal States in whose EEZs the presumed acts of sabotage recently occurred. This makes it easier for Estonia and Finland to theoretically claim the right of self-defence in response to these incidents should it be proven that a third State orchestrated the attack. However, one might argue that in the context of the ICJ’s ‘scale and effects’ test, the incidents were not sufficiently grave for invoking the right of self-defence given that they caused no significant disruption of critical services from the perspective of telecommunications and electrical grid.


The Significance of Safety Zones for the Protection of Offshore Critical Infrastructure

In any event, the above-referred incidents demonstrate that European coastal States need to establish safety zones under Article 60(4-6) of UNCLOS around all important objects of offshore infrastructure located in the EEZ and take rigid measures to track movements in the safety zones as well as ensure swift enforcement against violations in the safety zones.

Admittedly, some states that are keen on protecting the freedom of navigation in the EEZ (which includes anchoring), have interpreted Article 60(4-6) of UNCLOS in a way that prevents the establishment of safety zones around submarine cables and pipelines (see, e.g., Norway’s position here). Yet, for example, under the Danish legislation (see here and here), it is prohibited for ships to anchor, without urgent necessity, in the 400-metres-wide safety zones around submarine cables and pipelines and where, in a situation of urgent necessity, a ship has anchored in a safety zone around a cable or pipeline, then the master of the ship is obliged to immediately inform the Admiral Danish Fleet of the anchoring.  

If Estonia and Finland had put such measures in place, then a Russian commercial ship could likely not have remained in the vicinity of the Balticconnector pipeline and the Estonian-Finnish submarine cable three days in a row during the weekend when the pipeline and cable were damaged.

Image: ‘Pipes for cargo oil and inert gas on the VLCC Algarve’, by Hervé Cozanet (Creative Commons  Attribution-Share Alike 3.0 Unported).

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