Scenario 16: Cyber attacks against ships on the high seas

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Matti Mattila: Bridge of a sailing ship. CC-BY-NC-SA 2.0

This scenario considers a series of cyber operations against merchant vessels and warships on the high seas from the perspective of public international law. It analyses in particular issues related to jurisdiction and freedom of navigation on the high seas, as well as whether the cyber operations amounted to a prohibited use of force.

1 Scenario[edit | edit source]

1.1 Keywords[edit | edit source]

high seas, jurisdiction, freedom of navigation, sovereign immunity, countermeasures, use of force, intervention

1.2 Facts[edit | edit source]

[F1] State A and several other States have all agreed to pass domestic legislation that prevents companies incorporated in their territory from selling certain prohibited goods to State C. State A argues that this is justified by security concerns about how these goods would be used. The legislation grants State A the power to request the cargo manifests of ships bound for State C which depart from any of State A’s ports as well as the power to search any of State A’s flagged ships for the prohibited goods. State B has refused to follow State A’s actions and publicly stated that it does not believe the goods should be prohibited, and would continue to permit the sale of these goods to State C. The sale of these goods has not been prohibited under international law.

[F2] State A has since made numerous public statements criticising State B for not passing similar legislation. In these statements, State A has suggested it might stop and investigate ships that depart from State B and are under State B’s jurisdiction that are bound for State C if there are reasonable grounds to believe that there are prohibited goods on-board. In response, State B has sent two warships to the high seas that are adjacent to the exclusive economic zone of State A, to prevent any searches.

[F3] A month after State A enacted the legislation, State B discovers that the cyber infrastructure belonging to government custom officials in State B’s main port has been breached. State B determines that the breach originated from a targeted spear-phishing campaign against the computer systems in the customs agency headquarters. Malware installed as a result of the spear-phishing campaign has enabled the perpetrator to gain access to the shipping schedules and cargo manifests belonging to many of the ships that have departed from State B, destined for State C. This information has been classed as sensitive by State B in the aftermath of the legislation passed by State A and others. In the following days, State B traces the cyber operation to the Cyber Branch of State A’s military (incident 1).

[F4] Two weeks after the discovery of the unauthorised access into the computer systems of the customs agency, State B’s coastguard (a branch of State B’s military force) receives a distress signal from a merchant vessel registered to State B. The captain of the vessel states that their on-board navigational systems are suffering from significant interference as they sail through the high seas adjacent to State A’s exclusive economic zone, making navigation dangerous and increasing the risk to the crew and the vessel. An investigation traces the interference to an Advanced Persistent Threat (APT) group that has achieved a foothold in the ship’s network through a spear-phishing campaign targeting crew members. The network was not segmented, thus giving the APT group real-time access to multiple systems across the ship, including the navigation systems. The sophistication of the APT operation, and the similarity with the above described spear-phishing campaign against State B’s government customs officials, leads State B to attribute the operation to the Cyber Branch in State A (incident 2).

[F5] To protect the merchant vessel from any possible boarding threat, State B’s coastguard commands one of the nearby warships dispatched to the high seas to assist the merchant vessel. The warship reports that there has been disruption to its navigational radar capabilities and that it is unable to locate the merchant vessel. State B traces the source of the interference to the same APT group responsible for the interference with the merchant vessel’s on-board navigational systems. State B therefore attributes the interference to the Cyber Branch in State A (incident 3).

[F6] To end both operations, State B infects a computer in the Foreign Office of State A with a virus designed to render the machine permanently unusable, and that spreads across the network to other computers. In the aftermath of incident 1and whilst the cyber operation was continuing against the customs officials, this weakness was identified by State B as being exploitable if needed. State A’s Foreign Office shares a building with the Cyber Unit, and it is believed by State B that they may share the same network. The purpose is to stop the cyber operations of State A against State B, conducted by State A’s Cyber Branch (incident 4).

[F7] All concerned States are parties to the United Nations Convention on the Law of the Sea (UNCLOS).[1]

1.3 Examples[edit | edit source]

2 Legal analysis[edit | edit source]

For a general overview of the structure of analysis in this section, see Note on the structure of articles.

[L1] The analysis below will consider whether any of incidents 1–3 would be classed as a violation of international law, with a particular focus on the cyber operations against the two vessels. The analysis will then consider whether the response in incident 4 would be lawful under international law.

2.1 Attribution[edit | edit source]

2.1.1 State organs and exercise of governmental authority[edit | edit source]

State organs and persons and entities in exercise of governmental authority
The following types of conduct of State organs and persons and entities in exercise of governmental authority are attributable to a State:
  1. The conduct of any of the organs of that State, "whether the organ exercises legislative, executive, judicial or any other functions, whatever position it holds in the organization of the State, and whatever its character as an organ of the central Government or of a territorial unit of the State";[2]
  2. The conduct of an organ of another State placed at the disposal of the State in question, if "the organ is acting in the exercise of elements of the governmental authority" of the latter State;[3]
  3. The conduct of "a person or entity which is not an organ of the State […] but which is empowered by the law of that State to exercise elements of the governmental authority, […] provided the person or entity is acting in that capacity in the particular instance."[4]

Such conduct is attributable to the State even if the organ, person or entity acting in that capacity "exceeds its authority or contravenes instructions" (acts ultra vires).[5]

[L2] The Cyber Branch of State A’s military, which is responsible for the cyber operations in incidents 1, 2 and 3, is an organ of State A; its conduct is therefore attributable to State A.[6]

2.2 Breach of an international obligation[edit | edit source]

2.2.1 Prohibition of intervention[edit | edit source]

Prohibition of intervention
The obligation of non-intervention, a norm of customary international law prohibits States from intervening coercively in the internal or external affairs of other States. Prohibited intervention was authoritatively defined by the International Court of Justice in the judgment on the merits in the 1986 case Nicaragua v United States:

A prohibited intervention must … be one bearing on matters in which each State is permitted, by the principle of State sovereignty, to decide freely. One of these is the choice of a political, economic, social and cultural system, and the formulation of foreign policy. Intervention is wrongful when it uses methods of coercion in regard to such choices, which must remain free ones.[7]

In order for an act, including a cyber operation, to qualify as a prohibited intervention, it must fulfil the following conditions:
  1. The act must bear on those matters in which States may decide freely. The spectrum of such issues is particularly broad and it includes both internal affairs (such as “choice of a political, economic, social, and cultural system”[7] or the conduct of national elections[8]), and external affairs (“formulation of foreign policy”;[7] “recognition of states and membership of international organisations”[8])—the so-called domaine réservé of States.[9] The content of the domaine réservé is determined by the scope and nature of the state's international legal obligations.
  2. The act must be coercive in nature. There is no generally accepted definition of “coercion” in international law. However, in the cyber context, the Tallinn Manual 2.0 suggests that “the coercive effort must be designed to influence outcomes in, or conduct with respect to, a matter reserved to a target State”.[10] The “key is that the coercive act must have the potential for compelling the target State to engage in an action that it would otherwise not take (or refrain from taking an action it would otherwise take)”.[11] This approach distinguishes coercing or compelling the target State from merely influencing it by persuasion or propaganda and from causing nuisance without any particular goal.[12] The element of coercion also entails the requirement of intent.[13]
  3. Finally, there has to be a causal nexus between the coercive act and the effect on the internal or external affairs of the target State.[14]

[L3] With respect to the first prong of the test, the targets of the cyber operations in incidents 1 and 3 were predominantly governmental and run by State B. This means that State B normally had a significant amount of freedom in deciding how they are used, and thus the operations may well have had a bearing on its domaine réservé.

[L4] Incident 2 could also fall within the domaine réservé of State A. Although shipping is subject to some international regulation (notably the regime of the UN Convention on the Law of the Sea or UNCLOS), States retain considerable freedom to pursue their own policies concerned with shipping, and thus as long as “these did not otherwise violate international law”, shipping would likely fall within the domaine réservé of the relevant States. [15] In fact, targeting shipping has been recognised as a form of economic coercion (a form of intervention), which further suggests that it falls within the domaine réservé of State A.[16]

[L5] It is less clear whether the second prong of the test, the criterion of coercion, was met. The cyber operations in incidents 1-3 must be coercive in nature, meaning that the operations had the potential for compelling State B to act (or refrain from acting) in a way that it would not otherwise have done.[17]

[L6] For this reason, the cyber operation in incident 1 is unlikely to be coercive. The operation resulted in sensitive data being accessed by State A. However, this alone is unlikely to compel State B to change the way it acts regarding the sale of certain goods to State C, thus lacking the coercive element needed to satisfy the conditions above.

[L7] In contrast, incidents 2 and 3 are more likely to possess the coercive element necessary. Given that the criterion is that the act should be one which compels “the target State to engage in an action that it would otherwise not take”,[18] it is likely that the cyber operation in incident 2 would achieve this. If State B feared that cyber operations against ships bound for State C might pose serious risk to the safety of its crew and the vessels themselves, then this apprehension may indeed bring about a change in State B’s actions.

[L8] The cyber operation in incident 3 would also likely possess the required coercive element by potentially compelling State B to refrain from assisting its merchant vessels, or from dispatching warships to that area of the high seas.

[L9] Incidents 2 and 3 are therefore likely to qualify as a prohibited intervention under international law. This is subject to an important caveat; if these incidents were considered as amounting to a legitimate maritime law enforcement operation (see paras L21–L25 below), they would not constitute an intervention prohibited by international law.

2.2.2 Flag State jurisdiction[edit | edit source]

Flag State jurisdiction

Pursuant to the law of the sea, a ship has the nationality of the State whose flag it is entitled to fly.[19] In turn, that State has the exclusive jurisdiction over the ship in question while the ship is on the high seas.[20] Conversely, other States are prohibited from exercising enforcement jurisdiction[21] over a vessel that does not fly their flag.[22]

This principle of the exclusive jurisdiction of the flag State is a corollary of the rights enjoyed by vessels on the high seas – notably the freedom of navigation – as it serves to prevent interference by other States on the high seas.[23] However, the principle is subject to specific exceptions which enable third States to exercise enforcement jurisdiction over vessels that do not fly their flag.

One exception is provided by Article 110 of the Law of the Sea Convention,[24] which grants a ‘right of visit’ to States that are not the vessel’s flag State. Under the right of visit, a State may send a designated vessel to visit and inspect a foreign private vessel.[25] The exercise of this right is dependent on there being “reasonable ground for suspecting” that the vessel is engaged in piracy,[26] slavery,[27] or unauthorised broadcasting,[28] or that the vessel is either without nationality or, in reality, of the same nationality as the inspecting State.[29] Whether the right of visit may be carried out using cyber means is unclear and disputed.[30]

However, the Law of the Sea Convention does not represent the totality of the legitimate exceptions to flag State jurisdiction. The ability to exercise enforcement jurisdiction over foreign vessels may also be provided for in other international treaties.[31] Moreover, the United Nations Security Council, acting under Chapter VII of the UN Charter, may pass resolutions that compel member States to engage in enforcement actions at sea, usually with the flag State’s consent.[32] Very few resolutions have required States to exercise their enforcement jurisdiction over foreign vessels without the flag-State’s consent.[33]

[L10] State B is the flag State of the merchant vessel in incident 2, thus it possesses flag State jurisdiction over the vessel. In accordance with the principle of the exclusive jurisdiction of the flag State, no State other than State B is permitted to interfere with the vessel unless one of the exceptions outlined above may be identified.

[L11] The domestic legislation passed in State A provided that State with the authority to request and collect the cargo manifests of ships flying its flag and travelling to State C, and also to search any of such ships. However, this does not amount to an authority to search or interfere with ships that do not fly the flag of State A.

[L12] State A is not the flag State of the vessel in question. State A therefore cannot exercise its enforcement jurisdiction against the vessel. As such, the cyber operations against the vessel, which resulted in the interference with the vessel’s navigation systems would amount to a breach of State A’s international obligations, unless it could be shown that an exception existed which justified the interference (discussed below).

2.2.3 Freedom of navigation[edit | edit source]

Freedom of navigation

Article 87(1) UNCLOS provides for the freedom of navigation with respect to ships on the high seas.[34] This freedom is also found in other treaties[35] and in customary international law.[36]

In accordance with the freedom of navigation, every State has the right to sail ships flying its flag on the high seas[37] without being subject to the jurisdiction of other States.[38] In essence, this means that the ship has “the right to traverse the high seas with no or minimal interference from any other State”.[39]

In the Norstar judgment, the International Tribunal for the Law of the Sea (ITLOS) considered that any interference with a ship’s navigation by a foreign State would breach Article 87 UNCLOS,[40] including those acts of interference, which are not physical in nature.[41] According to the Tribunal, non-physical acts of interference may constitute a breach of the freedom of navigation, even if they do not involve enforcement or if they do not produce a ‘chilling effect’ on the flag State.[42] This suggests that non-enforcement cyber operations by non-flag States also qualify as breaches of the freedom of navigation, provided that they impermissibly interfere with navigation of a foreign vessel on the high seas.

To be lawful, any interference with a vessel’s freedom of navigation must be provided for in the UNCLOS regime (notably the right of visit[43] and hot pursuit[44]), in another international treaty,[45] or in customary international law.

[L13] State A’s cyber operation against State B’s merchant vessel (incident 2) could also amount to a breach of the freedom of navigation. The cyber operation against the vessel’s navigation systems has impeded that ship’s navigation, resulting in the captain’s decision to transmit a distress signal. That the interference was conducted through cyber means is immaterial as it has been held that an interference does not need to be physical in nature in order to qualify as a breach of the freedom of navigation.[46]

[L14] There are two possible grounds that State A could advance as justifications for its interference with the merchant vessel. It would be entitled to exercise enforcement jurisdiction in relation to State B’s vessel if it had either a “specific allocation of authority under international law”[47] (i.e., the exceptions provided for in UNCLOS and other regimes), or the consent of State B to act.[48]

[L15] Under UNCLOS, State A would have to have had “reasonable grounds to suspect” that one of the relevant exceptions had existed on board the merchant vessel.[49] However, State A did not make any claim that any of these exceptions applied in relation to State B’s merchant vessel. On the contrary, State A’s public statements that it would stop and search ships that may have prohibited goods on board suggest that its motivation for interference with the merchant vessel was extraneous to the grounds permitted by UNCLOS. In addition, the scenario does not mention any other applicable treaty that would permit such an interference, nor any relevant resolution of the UN Security Council. As such, it would be difficult to argue that there existed a specific allocation of authority under international law for State A to justifiably exercise its enforcement jurisdiction.

[L16] Similarly, State B has not given its consent for State A to exercise enforcement jurisdiction over the merchant vessel.

[L17] The cyber operation against the merchant vessel by State A would therefore amount to a violation of State B’s freedom of navigation on the high seas.

2.2.4 Sovereign immunity[edit | edit source]

Sovereign immunity

The Law of the Sea Convention grants sovereign immunity to specific vessels.

The first class of vessels afforded sovereign immunity are warships, defined as “ship[s] belonging to the armed forces of a State bearing the external marks distinguishing such ships of its nationality, under the command of an officer duly commissioned by the government of the State and whose name appears in the appropriate service list or its equivalent, and manned by a crew which is under regular armed forces discipline”.[50] Warships are considered “an expression of the sovereignty of the State whose flag [they] fl[y]”[51], and are afforded immunity in the internal waters of a third State,[52] in the territorial sea of a third State,[53] and on the high seas.[54]

Sovereign immunity is also granted to government vessels operated for non-commercial purposes.[55]

Vessels possessing sovereign immunity on the high seas “have complete immunity from the jurisdiction of any State other than the flag State”[56]. ‘Complete immunity’ means that sovereign immune vessels cannot be subjected “to any act of civil, criminal, or other jurisdiction of another State”, which includes any enforcement measure by a non-flag State.[57] Notably, this prevents a non-flag State from exercising the right of visit.[58]

This complete immunity is applicable in the territorial waters of a coastal State, subject to the requirements that a sovereign immune vessel must comply with the coastal State’s regulations concerning passage through its waters[59], and that the flag State of the immune vessel must bear responsibility for any damage that arises from its failure to comply with such regulations.[60] Sovereign immunity is also maintained within a foreign State’s internal waters[61] subject to diplomatic clearance, and within archipelagic waters.[62]

Any interference with cyber infrastructure on board a vessel that possesses sovereign immunity constitutes a violation of international law.[63] In this context, the notion of interference includes any activity that damages or significantly impairs the operation of the cyber infrastructure in question.[64]

Sovereign immunity is not absolute and can cease to apply as between States that are parties to an international armed conflict.[65]

[L18] There was no international armed conflict between States A and B. Accordingly, the immunity of State B’s warship targeted by the cyber operation in incident 3 did not cease to apply as between those States.

[L19] As such, the warship had complete immunity and could not be interfered with in any way. The radar disruption suffered by the warship amounted to an impermissible interference, as the cyber operation significantly impaired the radar infrastructure by undermining its ability to locate the merchant vessel.

[L20] Therefore, the cyber operation against State B’s warship qualified as a breach of the sovereign immunity afforded to the warship under the UNCLOS regime.

2.2.5 Maritime law enforcement operations[edit | edit source]

Maritime law enforcement

States possess the ability to engage in maritime law enforcement operations across various maritime domains. Maritime law enforcement operations refer to the actions a State can take when exercising their enforcement jurisdiction.

States are accorded rights and duties permitting responses to a range of maritime crimes or other unlawful acts. The extent of these duties is determined by the maritime zone involved.[66] Within its internal waters or territorial sea, a State may enforce its national laws, and exercise enforcement jurisdiction over non-sovereign immune vessels which engage in terrorism, transnational crimes, intentional pollution, illegal fishing, and intelligence gathering.[67]

A State’s authority to exercise its enforcement jurisdiction over non-sovereign immune vessels in its contiguous zone is limited to actions necessary to prevent infringement of its customs, fiscal, immigration or sanitary laws and regulations.[68] Within its own exclusive economic zone, a State has enforcement jurisdiction only over laws concerning fishing and pollution.[69]

The jurisdiction to enforce the laws on the high seas is generally vested in the flag State, which possesses the exclusive jurisdiction over that vessel.[70] However, there are exceptions to this rule, which can enable a State to exercise enforcement jurisdiction over a foreign vessel as part of a maritime law enforcement operation on the high seas. These exceptions can be found within the Law of the Sea Convention,[71] multilateral treaties,[72] bilateral treaties,[73] and UN Security Council Resolutions.[74]

As part of a maritime law enforcement operation, force may be used against foreign vessels.[75] However, forcible measures against foreign vessels at sea can also constitute a use of force under Article 2(4) of the UN Charter,[76] which is applicable in the maritime domain.[77] Therefore, forcible operations at sea must be distinguished as involving either a use of force under Article 2(4) or as being a maritime law enforcement operation.

Whether an operation is classed as law enforcement or military action engaging Article 2(4) is based “primarily on an objective evaluation” considering the relevant circumstances of each case.[78] It has also been held that the relevant question is “whether the dispute itself concerns military activities, rather than whether a [State] has employed its military in some manner in relation to the dispute”.[79] The focus when differentiating between maritime law enforcement activities and uses of force under Article 2(4) is on the objective assessment of the activities involved in any incident.

Whenever force is used in law enforcement operations, certain conditions must be complied with. Any use of force in law enforcement must be used as a last resort and not go beyond what is reasonable and necessary in the circumstances.[80] Prior to using force, any law enforcement operation should have attempted to use a range of actions, including using auditory or visual signals requesting a ship to stop, or firing a shot across the bow.[81] If force is used, “all efforts should be made to ensure that life is not endangered”.[82]

When the vessel concerned possesses sovereign immunity, it is generally considered that any exercise of enforcement jurisdiction against such a vessel will be considered a use of force under Article 2(4) rather than as a law enforcement operation,[83] as States are prohibited from exercising jurisdiction over sovereign immune vessels.[84] It has been held that when military forces of one State, and military and paramilitary forces of another State are arrayed in opposition to each other, this will be considered as a ‘quintessentially military situation’, and not as involving law enforcement.[85]

Whether cyber means can be used in maritime enforcement operations is a point of discussion. It has been recognised that in light of improving technologies, the rules concerning maritime law enforcement operations may need to be reviewed.[86] For example, it is disputed whether the right of visit could be carried out virtually through cyber means.[87]

[L21] The cyber operation in incident 2 may be considered as a law enforcement operation. Circumstances that would support such a conclusion include that the cyber operation was not intended to defend State A against a threat to its sovereignty,[88] but rather to prevent the passage of a vessel.[89] If the cyber operation was preceded by the attempted arrest and charging of those on the merchant vessel, this would also support qualifying the operation as law enforcement.[90] However, the isolated nature of the cyber operation against the merchant vessel, and the lack of prior circumstances suggesting a law enforcement action[91] may undermine the operation’s classification as maritime law enforcement.

[L22] If the cyber operation in incident 2 was characterised as a law enforcement operation, it would be likely to be classed as unlawful. The lack of a valid jurisdictional basis would support a finding of unlawfulness. State A had no jurisdictional basis to conduct a cyber operation against the merchant vessel, as it was not the flag State of the vessel, nor did it have the flag State’s consent. The exceptions that can grant jurisdiction over foreign flagged vessels also do not apply in this scenario (see paras L14-L16 above).

[L23] In addition, the actions taken would likely have also breached the standards imposed on enforcement operations. The cyber operation was the first measure used, thus not meeting the requirement that auditory or visual signals should be used first. Moreover, the interference with the navigation systems caused by the cyber operation had the potential to result in the death or injury to the crew and severe damage to the ship. State A would thus likely have failed to make all efforts to ensure life would not be endangered.[92]

[L24] In contrast, incident 3 is more likely to concern a use of force under Article 2(4) of the UN Charter. This is the general presumption when vessels possessing sovereign immunity are subject to a foreign state’s enforcement jurisdiction.[93]

[L25] In addition, the cyber operation targeting the warship interfered with its ability to assist and to protect the merchant vessel. There were also no pre-existing circumstances that could be considered as being suggestive of law enforcement,[94] given that the cyber operation was the first occurrence of any action against the warship in incident 3. The military nature of the Cyber Branch in State A responsible for the cyber operation may support the finding of a military situation with two military forces in opposition to each other.

2.2.6 Use of force[edit | edit source]

Use of force
Article 2(4) of the UN Charter prescribes States to “refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the purposes of the United Nations”.[95] This prohibition is reflective of customary international law[96] and it is frequently described as a peremptory norm of international law.[97] However, the notion of “force” in this context is limited to armed force[98], and to operations whose scale and effects are comparable to the use of armed force.[99]

At present, there is a debate as to whether cyber operations with no physical effects may amount to a prohibited use of force. It has been argued that disruptive cyber operations of this kind fall under the scope of Article 2(4) if the resulting disruption is “significant enough to affect state security”.[100] Undoubtedly, one of the purposes of the prohibition of force under international law is to safeguard the national security of the potentially affected States.[101] However, many forms of outside interference including various forms of political and economic coercion may affect the national security of the victim State. And yet, the drafters of the UN Charter had expressly rejected the proposal to extend the prohibition of force beyond the strict confines of military (or armed) force.[102] This is reflected also in the preamble, which explicitly stipulates that the drafters sought “to ensure, by the acceptance of principles and the institution of methods, that armed force shall not be used, save in the common interest”.[103]

In principle, it could be argued that the notion of “force”, like other generic terms in treaties of unlimited duration, should be presumed to have an evolving meaning.[104]

As of 2020, there is limited State practice supporting the claim that the meaning of “force” has evolved to include non-destructive cyber operations against critical national infrastructure[105] and no victim State of an operation of this kind has suggested that the operation would have amounted to a use of force.[106] However, States have begun addressing this question. In particular, France[107] and the Netherlands[108] allow for the possibility of cyber operations, which do not produce physical effects, to qualify as uses of force, if certain criteria are met. These criteria include the seriousness and reach of a given cyber operation’s consequences and its military nature,[109] as well as “the circumstances prevailing at the time of the operation, such as the origin of the operation and the nature of the instigator (military or not), the extent of intrusion, the actual or intended effects of the operation or the nature of the intended target”.[110] Several of these criteria are also reflected in the Tallinn Manual 2.0.[111]

Even if an operation does not meet the threshold of the use of force, it may still be considered a violation of other rules of international law.[112] In this regard, the prohibition of non-intervention, the obligation to respect the sovereignty of other States, and the possible obligation to refrain from launching cyber operations against other States’ critical infrastructure are all of potential relevance.

[L26] Incident 1 would be unlikely to be considered as a use of force. The severity of the operation was minimal; the data which was accessed was not corrupted or deleted, and the infrastructure that it was stored on remained functional after the incident. Though the access was invasive, the lack of significant consequences militates against considering the operation as a use of force.

[L27] Incidents 2 and 3 would have to be distinguished as potential uses of force under Article 2(4) of the UN Charter rather than maritime law enforcement operations (see section 2.2.5 above) in order for the following analysis to apply.

[L28] With respect to incident 2, the cyber operation would likely lack the necessary severity due to the absence of physical harm to the individuals on board the vessel and because the navigation’s loss of functionality was only temporary in nature. As such, it is unlikely that the cyber operation would reach the threshold of a prohibited use of force.

[L29] In contrast, the cyber operation against the warship (incident 3) impacted the functionality of the radar to the point that the merchant vessel could no longer be located. This interference with the warship’s systems could be considered as severe. Though the operation did not result in direct physical harm, it arguably interfered with State B’s critical national interest[113] by impacting the functionality of one of its warships and by undermining its ability to assist and protect its merchant vessels.

[L30] Moreover, the military nature of the vessel means the targeted systems were of a greater concern to State B.[114] The cyber operation would also be considered military in character as it can be attributed to the military Cyber Branch in State A.[115] Both of these considerations would further support classifying the cyber operation as a use of force.

[L31] An isolated attack against a warship can be sufficient to engage the right to self defence provided it reaches the threshold of an armed attack.[116] However, it is unlikely that the cyber operation in incident 3 would be considered as a grave use of force sufficient to amount to an armed attack[117] due to the absence of death or injury to persons, or the destruction of property.[118]

2.3 Permissible responses by State B[edit | edit source]

[L32] Once it has been established that State A’s conduct amounted to an internationally wrongful act, State B may have the right to resort to countermeasures.

2.3.1 Countermeasures[edit | edit source]

Countermeasures
Countermeasures are “measures that would otherwise be contrary to the international obligations of an injured State vis-à-vis the responsible State, if they were not taken by the former in response to an internationally wrongful act by the latter in order to procure cessation and reparation”.[119] Several States, including Austria,[120] Estonia,[121] France,[122] Germany,[123] Japan,[124] the Netherlands,[125] the United Kingdom,[126] and the United States,[127] have expressly confirmed the applicability of the law of countermeasures to cyber operations. Others, including Brazil,[128] China,[129] and Cuba,[130] have expressed caution in this regard. Countermeasures should be distinguished from retorsions, which are unfriendly but lawful acts by the aggrieved party against the wrongdoer.

As a matter of general international law, an injured State may only take countermeasures against the responsible State if the following conditions are met:

  1. The existence of a prior internationally wrongful act of the responsible State against the injured State;[131]
  2. The internationally wrongful act has not ceased and “the dispute is [not] pending before a court or tribunal which has the authority to make decisions binding on the parties”, unless the “responsible State fails to implement the dispute settlement procedures in good faith”;[132]
  3. The injured State has called upon[133] the responsible State to fulfil its obligations arising from its internationally wrongful act;[134] and
  4. The injured State has notified the responsible State of its decision to take countermeasures, and offered to negotiate with that State, unless it is taking “urgent countermeasures as are necessary to preserve its rights.”[135]

Additionally, the countermeasures must fulfil the following requirements:

  1. Their aim must be to induce the responsible State to comply with the legal consequences of its internationally wrongful act;[136] in other words, the aim of countermeasures is restoration, not retribution; and the countermeasures can only target the responsible State;
  2. They “shall, as far as possible, be taken in such a way as to permit the resumption of performance of the obligations in question;”[137]
  3. They shall not affect “obligations under peremptory norms of general international law”[138], obligations under any dispute settlement procedure between the injured and responsible State, and obligations arising from the inviolability of diplomatic or consular agents, premises, archives and documents;[139] and
  4. They must be “commensurate with the injury suffered, taking into account the gravity” of the prior unlawful act and of the rights in question (i.e. the requirement of “proportionality”).[140]

Taken countermeasures must be suspended if the internationally wrongful act has ceased or if “the dispute is pending before a court or tribunal which has the authority to make decisions binding on the parties”, and they must be terminated as soon as the responsible State has complied with its (secondary) obligations.

There is a debate as to whether States that have not themselves been directly injured by an unlawful cyber operation may engage in countermeasures in support of the injured State (sometimes referred to as collective countermeasures).[141] In particular, one State has recently put forward the view that non-injured States “may apply countermeasures to support the state directly affected by the malicious cyber operation”.[142] This would apply where diplomatic action is insufficient, but no lawful recourse to use of force exists. This interpretation would allow States to offer active assistance to States, which may not possess sufficient cyber capabilities themselves to counter an ongoing unlawful cyber operation. This view has found some support in scholarship,[143] but was since rejected by at least one other State,[144] with other parts of scholarship reluctant to endorse it.[145] Therefore, it has to be regarded as a call for progressive development of international law, rather than a statement of the current state of international law.

Whether a particular measure fulfils these conditions is an objective question,[146] while the burden of proof that the relevant conditions have been fulfilled falls on the injured State.[147] The exact standard of proof required is unsettled in international law and it will depend on the relevant forum. However, relevant international jurisprudence tends to rely in this regard on the standard of “clear and convincing evidence”.[148] This standard translates in practice into a duty to “convince the arbiter in question that it is substantially more likely than not that the factual claims that have been made are true.”[149] Importantly, if a State does resort to countermeasures on the basis of an unfounded assessment that a breach has occurred, it may incur responsibility for its own wrongful conduct.[150]

[L33] State B launched a cyber operation against State A’s Foreign Office with the aim to end cyber operations against it (incident 4). International law permits it to take countermeasures in order to bring to an end those actions by State A that qualify as internationally wrongful acts. Incidents 2 and 3 arguably amounted to internationally wrongful acts (see paras L12, L17, and L20 above).

[L34] Countermeasures cannot be anticipatory; they must only be taken in response to an internationally wrongful act.[151] The vulnerability in the Foreign Office was identified prior to the cyber operations against the vessels; however, the operation against the computer in the Foreign Office was not launched until after the cyber operations in incidents 2 and 3. Therefore, the countermeasure would not qualify as anticipatory.

[L35] State B, before taking countermeasures, should normally call upon State A to fulfil its international obligations (i.e., to cease the operations against State B) and notify State A of its intention to take countermeasures.[152] However, this has been recognised as incompatible with the purpose of many cyber countermeasures (as it may enable the opposing state to mitigate or avoid the effects of the countermeasure).[153] This position has also been recognised by one State.[154] The duty to notify State A may then be precluded due to the urgency of the countermeasures that are needed to preserve the rights of State B.[155] Given the immediacy of the internationally wrongful act that was being committed against the two vessels, it is unlikely the countermeasure would require notification, as to notify State A of it would likely undermine its purpose and provide State A with an opportunity to mitigate the consequences of the operation.

[L36] The issue with the countermeasure used is that it may fail the test of proportionality. This requires that “the effects of a countermeasure must be commensurate with the injury suffered”[156] considering the “gravity of the internationally wrongful act and the rights in question”.[157] This determines the type and intensity of the countermeasure available to State B.[158]

[L37] In incident 2, the cyber operation had the potential to result in death or injury to the crew, or result in substantial damage to the vessel itself. Similar consequences were possible in incident 3. However, the actual consequence was a loss of functionality, albeit for critical systems essential when a vessel is under way, which created the distinct possibility of physical harm to persons or physical damage to the vessel.

[L38] In contrast, incident 4 concerned the spreading of a virus through a computer network which aimed to irreparably damage the infrastructure. Accompanying this, State B was targeting the Foreign Office on the basis that they may share the same network as the Cyber Branch resulting in widespread effects across State A departments.

[L39] Judging whether a supposed countermeasure is proportionate is necessarily an ‘approximation’.[159] Ultimately, this can make forming a conclusive judgment on proportionality difficult, as in this case. It could be argued that the possible consequences of the operations in incidents 2 and 3 exceeded the consequences in incident 4,thus making the countermeasure commensurate. If the consequences in incidents 2 and 3 escalated to death or injury to the crew, or significant damage to the ship as a whole, it is likely that the countermeasure would be proportionate. However, as these possible consequences did not materialize, it may be that the widespread permanent damage to the cyber infrastructure in State A’s Foreign Office would not be commensurate with the injury suffered by State B.

[L40] Finally, the purpose of the countermeasure should be to induce State A to comply with the legal consequences of the internationally wrongful act – the purpose cannot be retribution.[160] Therefore, countermeasures are to be used in such a way as to ‘permit the resumption of performance of the obligations in question’.[161] This has been considered to amount to an obligation to “limit conduct to means that are reversible as far as possible”[162], though this principle is not absolute.[163]

[L41] The virus that State B has used against the computer in State A’s Foreign Office offered little chance of any reversibility, as its purpose was to make the computers unusable and to spread quickly for maximum impact. The lack of reversibility suggests that the purpose was not to compel State A to comply with the legal consequences of the cyber operation, but rather to retaliate in response.

[L42] Overall, the response by State B would likely be considered as exceeding the bounds of permissible countermeasures under international law.

3 Checklist[edit | edit source]

  • Flag State jurisdiction
    • Has there been an unlawful interference by a foreign State with a vessel under the jurisdiction of another?
    • Did any of the exceptions permitting the foreign State to exercise its jurisdiction exist at the time?
  • Freedom of navigation
    • Has the cyber operation impacted the navigation of a foreign vessel?
  • Sovereign immunity
    • Has there been an interference with a foreign vessel that enjoys sovereign immunity?
    • Is there an international armed conflict in existence that would remove the sovereign immunity of the vessel?
  • Maritime law enforcement or use of force
    • Does an “objective evaluation” of the circumstances suggest the operation qualified as law enforcement, or as a use of force?
    • If law enforcement, have the standards for using forcible means in a law enforcement operation been adhered to?
    • If a potential use of force, has the cyber operation reached the threshold necessary for classification as a prohibited use of force under Article 2(4) of the UN Charter?
  • Countermeasures
    • Is the injured State responding to a prior internationally wrongful act of the responsible State?
    • Would the injured State’s conduct taken in response amount to an internationally wrongful act if not justified as a countermeasure?
    • Do the measures taken in response by the injured State meet the conditions prescribed for the lawful resort to countermeasures under international law?

4 Appendixes[edit | edit source]

4.1 See also[edit | edit source]

4.2 Notes and references[edit | edit source]

  1. United Nations Convention on the Law of the Sea (adopted 10 December 1982, entered into force 16 November 1994) 1833 UNTS 3 (UNCLOS).
  2. ILC Articles on State Responsibility, Art 4(1).
  3. ILC Articles on State Responsibility, Art 6.
  4. ILC Articles on State Responsibility, Art 5.
  5. ILC Articles on State Responsibility, Art 7; Tallinn Manual 2.0, commentary to rule 15, paras. 6-7 and 12.
  6. ILC Articles on State Responsibility, Art 4; see also ICRC Customary IHL Study, vol 1, 530–531 (“The armed forces are considered to be a State organ, like any other entity of the executive, legislative or judicial branch of government.”).
  7. 7.0 7.1 7.2 Military and Paramilitary Activities in and against Nicaragua (Nicaragua v US) (Merits) [1986] ICJ Rep 14, para 205.
  8. 8.0 8.1 Dutch Minister of Foreign Affairs, ‘Letter to the President of the House of Representatives on the International Legal Order in Cyberspace – Appendix: International Law in Cyberspace’ (5 July 2019), 3.
  9. See, for example, Katja Ziegler, “Domaine Réservé”, in Rudiger Wolfrum (ed), Max Planck Encyclopedia of Public International Law (OUP 2008) (updated April 2013) (defining the domaine réservé as those “areas where States are free from international obligations and regulation”).
  10. Tallinn Manual 2.0, commentary to rule 66, para 19.
  11. Tallinn Manual 2.0, commentary to rule 66, para 21; see also Dutch Minister of Foreign Affairs, ‘Letter to the President of the House of Representatives on the International Legal Order in Cyberspace – Appendix: International Law in Cyberspace’ (5 July 2019), 3.
  12. Tallinn Manual 2.0, commentary to rule 66, para 21.
  13. Tallinn Manual 2.0, commentary to rule 66, paras 19, 27.
  14. Tallinn Manual 2.0, commentary to rule 66, para 24 (The exact nature of the causal nexus was not agreed on).
  15. Terry D Gill, ‘Non-intervention in the Cyber Context’ in Katharina Ziolkowski (ed), Peacetime Regime for State Activities in Cyberspace (NATO CCD COE 2013) “…a State from pursuing its own political, economic and cultural policies, as long as these did not otherwise violate international law…in which case the matter would not qualify as an essentially domestic one”.
  16. Philip Kunig, ‘Prohibition of Intervention’, in Rüdiger Wolfrum (ed) Max Planck Encyclopedia of Public International Law (OUP 2008-, updated April 2008) para 26 (considering that “typical economic interventions are interference with trade and shipping”).
  17. Tallinn Manual 2.0, commentary to rule 66, para 21; see also Russel Buchan ‘Cyber Attacks: Unlawful Uses of Force or Prohibited Interventions?’ (2012) 17 Journal of Conflict and Security Law 212.
  18. Tallinn Manual 2.0, commentary to rule 66, para 21; see also M Jamnejad and M Wood, ‘Prohibition of Intervention’ (2009) 22 Leiden Journal of International Law 345, 347 “where coercive action is taken by one state to secure a change in the policies of another”.
  19. Law of the Sea Convention, Art 91(1).
  20. Law of the Sea Convention, Art 92(1). See also Doris König, ‘Flag of Ships’ in Rüdiger Wolfrum (ed) Max Planck Encyclopedia of Public International Law (OUP 2008-, updated April 2009) para 25.
  21. Enforcement jurisdiction refers to the authority of a State to secure compliance with legal rules. Restatement (Fourth) of the Foreign Relations Law of the United States (ALI 2018) § 401.
  22. The Case of the S.S. “Lotus” (Judgment No. 9) (1927) PCIJ Series A No 10, “It is certainly true that – apart from certain special cases which are defined by international law – vessels on the high seas are subject to no authority except that of the State whose flag they fly… no State may exercise any kind of jurisdiction over foreign vessels upon them”; see also M/V “Norstar” judgment (Panama v Italy) (2019) 25 ITLOS (herein referred to as the M/V “Norstar” Judgment), para 216 ”…save in exceptional cases, no State may exercise jurisdiction over a foreign ship on the high seas”; Doris König, ‘Flag of Ships’ in Rüdiger Wolfrum (ed) Max Planck Encyclopedia of Public International Law (OUP 2008-, updated April 2009) para 25.
  23. Y Tanaka, ‘Navigational Rights and Freedoms’ in (2015) in Donald Rothwell, Alex Oude Elfernik, Karen Scott and Tim Stephens The Oxford Handbook of the Law of the Sea (OUP 2015) 556.
  24. Law of the Sea Convention, Art 110 (1); the Convention makes clear that other exceptions contained in separate treaties can also exist, see for example the exceptions outlined in Convention for the Suppression of Unlawful Acts against the Safety of Maritime Navigation (entered into force 1 March 1992) 1678 UNTS 221 (SUA Convention).
  25. Law of the Sea Convention, Part VII, Art 110; Douglas Guilfoyle ‘The High Seas’ (2015) in Donald Rothwell, Alex Oude Elfernik, Karen Scott and Tim Stephens The Oxford Handbook of the Law of the Sea (OUP 2015) 220.
  26. Law of the Sea Convention, Part VII, Art 110 (1) (a).
  27. Law of the Sea Convention, Part VII, Art 110 (1) (b).
  28. Law of the Sea Convention, Part VII, Art 110 (1) (c).
  29. Law of the Sea Convention, Part VII, Art 110 (1) (d-e).
  30. Tallinn Manual 2.0, commentary to rule 46, para 10.
  31. Douglas Guilfoyle ‘The High Seas’ (2015) in Donald Rothwell, Alex Oude Elfernik, Karen Scott and Tim Stephens The Oxford Handbook of the Law of the Sea (OUP 2015) 219. See, e.g., the ship boarding arrangements between the US and other States as part of the Proliferation Security Initiatives, such as the Agreement between the Government of the United States of America and the Government of the Republic of Croatia concerning cooperation to suppress the proliferation of weapons of mass destruction, their delivery systems, and related materials (signed June 1 2005, entered into force 5 March 2007).
  32. See for example, UNSC Res 665 (14 August 1990) UN Doc S/Res/665; UNSC Res 2292 (14 June 2016) UN Doc S/Res/2292.
  33. See for example, UNSC Res 665 (25th August 1990) UN Doc S/Res/665. See also Craig H Allen, “The Peacetime Right of Approach and Visit and Effective Security Council Sanctions Enforcement at Sea” (2019) 95 INT’L L. STUD 400, 406.
  34. Law of the Sea Convention, Part VII, Art 87 (1).
  35. For example, the Geneva Convention on the High Seas (entered into force 30th September 1962) 450 UNTS 11, article 2(1).
  36. “Union of Soviet Socialist Republics-United States: Joint Statement with Attached Uniform Interpretation of Rules of International Law Governing Innocent Passage” (1989) 28 International Legal Materials 1444 (The Jackson Hole Statement).
  37. Law of the Sea Convention, Part VII, Art 90.
  38. M/V “Norstar” judgment, para 216 “Freedom of navigation would be illusory if a ship – a principal means for the exercise of the freedom of navigation – could be subject to the jurisdiction of other States on the high seas”.
  39. Albert Hoffman, ‘Freedom of Navigation’ in Rudiger Wolfrum Max Planck Encyclopaedia of Public International Law (OUP 2011) para 22.
  40. M/V “Norstar” judgment, para 222.
  41. M/V “Norstar” judgment, para 223.
  42. M/V “Norstar” judgment, para 224, referred to as a “chilling effect”.
  43. Law of the Sea Convention, Part VII, Art 110.
  44. Law of the Sea Convention, Part VII, Art 111.
  45. M/V “Norstar” judgment, para 224 “…save in exceptional cases expressly provided for in the Convention or in other international treaties…”; Y Tanaka, ‘Navigational Rights and Freedoms’ (2015) in Donald Rothwell, Alex Oude Elfernik, Karen Scott and Tim Stephens The Oxford Handbook of the Law of the Sea (OUP 2015) 556; see also Geneva Convention on the High Seas (entered into force 30th September 1962) 450 UNTS 11, Arts 22-23.
  46. M/V “Norstar” judgment, para 223.
  47. Tallinn Manual 2.0, rule 11 (a).
  48. Tallinn Manual 2.0, rule 11 (b).
  49. Law of the Sea Convention, Part VII, Art 110 (1).
  50. Law of the Sea Convention, Part VII, Art 29.
  51. The “Ara Libertad” Case (Argentina v. Ghana) (2012) ITLOS 20, para 94.
  52. The “Ara Libertad” Case (Argentina v. Ghana) (2012) ITLOS 20, para 95.
  53. Law of the Sea Convention, Part VII, Art 32.
  54. Law of the Sea Convention, Part VII, Art 95.
  55. Law of the Sea Convention, Part VII, Art 96.
  56. Law of the Sea Convention, Part VII, Art 95-96.
  57. Wolff Heintschel von Heinegg, ‘Warships’ (2015) in Rüdiger Wolfrum (ed) Max Planck Encyclopedia of Public International Law (OUP 2008-, updated October 2015).
  58. Law of the Sea Convention, Part VII, Art 110(1) (excepting ships ‘entitled to complete immunity’).
  59. Law of the Sea Convention, Part VII, Art 30.
  60. Law of the Sea Convention, Part VII, Art 31.
  61. Wolff Heintschel von Heinegg, ‘Warships’ (2015) in Rüdiger Wolfrum (ed) Max Planck Encyclopedia of Public International Law (OUP 2008-, updated October 2015).
  62. Donald Rothwell and Tim Stephens, The International Law of the Sea (Bloomsbury 2010).
  63. Tallinn Manual 2.0, rule 5; Michael Schmitt ‘Below the Threshold Cyber Operations: The Countermeasures Response Option and International Law’ (2014) 54 Virginia Journal of International Law 697.
  64. Ibid.
  65. Tallinn Manual 2.0, commentary to rule 5, para 6.
  66. Natalie Klein ‘Maritime Security’ in Donald Rothwell, Alex Oude Elfernik, Karen Scott and Tim Stephens (eds), The Oxford Handbook of the Law of the Sea (OUP 2015) 586.
  67. Natalie Klein ‘Maritime Security’ in Donald Rothwell, Alex Oude Elfernik, Karen Scott and Tim Stephens (eds), The Oxford Handbook of the Law of the Sea (OUP 2015) 586.
  68. Law of the Sea Convention, Part VII, Article 33.
  69. Law of the Sea Convention, Part VII, Article 73.
  70. M/V “Norstar” judgment (Panama v Italy) (2019) 25 ITLOS, para 216 ”…save in exceptional cases, no State may exercise jurisdiction over a foreign ship on the high seas”; Doris König, ‘Flag of Ships’ in Rüdiger Wolfrum (ed) Max Planck Encyclopedia of Public International Law (OUP 2008-, updated April 2009); Douglas Guilfoyle ‘The High Seas’ (2015) in Donald Rothwell, Alex Oude Elfernik, Karen Scott and Tim Stephens The Oxford Handbook of the Law of the Sea (OUP 2015).
  71. Law of the Sea Convention, Part VII, Art 110 – 111.
  72. See for example the Convention for the Suppression of Unlawful Acts against the Safety of Maritime Navigation (entered into force 1 March 1992) 1678 UNTS 221 (SUA Convention).
  73. See the ship boarding arrangements between the US and other States as part of the Proliferation Security Initiatives, eg Agreement between the Government of the United States of America and the Government of the Republic of Croatia Concerning Cooperation to Suppress the Proliferation of Weapons of Mass Destruction, their Delivery Systems, and Related Materials (Signed June 1 2005, entered into force March 5, 2007).
  74. See for example, UNSC Res 665 (14 August 1990) UN Doc S/Res/665.
  75. Patricia Kwast, ‘Maritime Law Enforcement and the Use of Force: Reflections on the Categorisation of Forcible Action at Sea in the Light of the Guyana/Suriname Award’ (2008) 13 Journal of Conflict and Security Law; The M/V Saiga Case (No 2) (Saint Vincent and the Grenadines v Guinea) ITLOS (Judgment 1999) (hereinafter referred to as the M/V Saiga Case) para 155; Case Concerning the Detention of Three Ukrainian Naval Vessels (Ukraine vs the Russian Federation) (Order for Provisional Measures 2019) ITLOS 26.
  76. Charter of the United Nations (adopted 26 June 1945, entered into force 24 October 1945) 1 UNTS 16, Art 2(4); Patricia Kwast, ‘Maritime Law Enforcement and the Use of Force: Reflections on the Categorisation of Forcible Action at Sea in the Light of the Guyana/Suriname Award’ (2008) 13 Journal of Conflict and Security Law, 58.
  77. Oil Platforms (Islamic Republic of Iran v United States of America) (Judgment) 2003 ICJ Rep 161; Patricia Kwast, ‘Maritime Law Enforcement and the Use of Force: Reflections on the Categorisation of Forcible Action at Sea in the Light of the Guyana/Suriname Award’ (2008) 13 Journal of Conflict and Security Law page 59; Law of the Sea Convention, Part VII, Art 301.
  78. Case Concerning the Detention of Three Ukrainian Naval Vessels (Ukraine vs the Russian Federation) (Order for Provisional Measures 2019) ITLOS 26, para 66.
  79. South China Sea Arbitration (The Republic of the Philipines and the Peoples Republic of China) (Award of the 12th July 2016) PCA Case No 2013-19 (herein referred to as the South China Sea Arbitration), para 1158.
  80. The M/V Saiga Case, para 155.
  81. The M/V Saiga Case, para 156.
  82. The M/V Saiga Case, para 156.
  83. Patricia Kwast, ‘Maritime Law Enforcement and the Use of Force: Reflections on the Categorisation of Forcible Action at Sea in the Light of the Guyana/Suriname Award’ (2008) 13 Journal of Conflict and Security Law, 85; Natalie Klein, Maritime Security and the Law of the Sea (OUP 2012) 65.
  84. Law of the Sea Convention, Part VII, Art 95-96; Wolff Heintschel von Heinegg, ‘Warships’ (2015) in Rüdiger Wolfrum (ed) Max Planck Encyclopedia of Public International Law (OUP 2008-, updated October 2015).
  85. The South China Sea Arbitration, para 1161.
  86. Natalie Klein ‘Maritime Security’ (2015) in Donald Rothwell, Alex Oude Elfernik, Karen Scott and Tim Stephens The Oxford Handbook of the Law of the Sea (OUP 2015).
  87. Tallinn Manual 2.0, commentary to rule 46, para 10.
  88. Patricia Kwast, ‘Maritime Law Enforcement and the Use of Force: Reflections on the Categorisation of Forcible Action at Sea in the Light of the Guyana/Suriname Award’ (2008) 13 Journal of Conflict and Security Law 49, 81.
  89. Case Concerning the Detention of Three Ukrainian Naval Vessels (Ukraine vs the Russian Federation) (Order for Provisional Measures 2019) ITLOS 26, para 72 (holding that a dispute concerning the interpretation of a regime of passage is not military in nature).
  90. Case Concerning the Detention of Three Ukrainian Naval Vessels (Ukraine vs the Russian Federation) (Order for Provisional Measures 2019) ITLOS 26, para 76.
  91. Ibid, para 73 (“After being held for about eight hours, the Ukrainian naval vessels apparently gave up their mission…and sailed away from it. The Russian Coast Guard then ordered them to stop and, when the vessels ignored the order…started chasing them. It was at this moment and in this context that the Russian Coast Guard used force…”).
  92. See The M/V Saiga Case, para 156.
  93. Patricia Kwast, ‘Maritime Law Enforcement and the Use of Force: Reflections on the Categorisation of Forcible Action at Sea in the Light of the Guyana/Suriname Award’ (2008) 13 Journal of Conflict and Security Law, 85; Natalie Klein, Maritime Security and the Law of the Sea (OUP 2012) 65.
  94. Ibid, para 73.
  95. Charter of the United Nations (adopted 26 June 1945, entered into force 24 October 1945) 1 UNTS 16 (UN Charter) art. 2(4).
  96. Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory (Advisory Opinion) [2004] ICJ Rep 136, para 87; Military and Paramilitary Activities in and against Nicaragua (Nicaragua v United States of America) (Merits) [1986] ICJ Rep 14, paras 187–190.
  97. See, for example,The International Law Commission, 'Document A/6309/ Rev.1: Reports of the International Law Commission on the second part of its seventeenth and on its eighteenth session' Yearbook of the International Law Commission Vol. II (1966) 247 (“The law of the Charter concerning the prohibition of the use of force in itself constitutes a conspicuous example of a rule in international law having the character of jus cogens”); Christine Gray, International Law and the use of force (OUP 2018) 32; Oliver Corten, The Law against War (Hart Pub. 2010) 44; Oliver Dörr and Albrecgr Randelzhofer, ‘Article 2(4)’ in Bruno Simma et al (eds), The Charter of the United Nations: A Commentary Vol I (OUP 2012), 231, para 67 (“the prohibition of the use of force laid down in Art. 2 (4) is usually acknowledged in State practice and legal doctrine to have a peremptory character, and thus to be part of the international ius cogens”).
  98. Oliver Dörr and Albrecht Randelzhofer, ‘Article 2(4)’ in Bruno Simma et al (eds), The Charter of the United Nations: A Commentary Vol I (OUP 2012) 208 para 16 (“The term [‘force’] does not cover any possible kind of force, but is, according to the correct and prevailing view, limited to armed force.”).
  99. Cf. Ian Brownlie, International Law and the Use of Force by States (OUP 1963) 362 (“[Art 2(4)] applies to force other than armed force”); Tallinn Manual 2.0, rule 69 (“A cyber operation constitutes a use of force when its scale and effects are comparable to non-cyber operations rising to the level of a use of force.”).
  100. Marco Roscini, Cyber Operations and the Use of Force in International Law (OUP 2014) 55.
  101. Cf. Charter of the United Nations (adopted 26 June 1945, entered into force 24 October 1945) 1 UNTS 16 (UN Charter) art. 2(4) (expressly prohibiting the use of force against the “political independence” of any State).
  102. Documents of the United Nations Conference on International Organization (1945), vol VI, 334.
  103. Charter of the United Nations (adopted 26 June 1945, entered into force 24 October 1945) 1 UNTS 16 (UN Charter) preamble.
  104. Cf. Dispute regarding Navigational and Related Rights (Costa Rica v Nicaragua) Judgment [2009 ICJ Rep 213], para 66 (“[W]here the parties have used generic terms in a treaty, the parties necessarily having been aware that the meaning of the terms was likely to evolve over time, and where the treaty has been entered into for a very long period or is ‘of continuing duration’, the parties must be presumed, as a general rule, to have intended those terms to have an evolving meaning”).
  105. However, such claims are occasionally made in the scholarship: see, for example, Marco Roscini, Cyber Operations and the Use of Force in International Law (OUP 2014) 59; Nicholas Tsagourias 'Cyber Attacks, Self-Defence and the Problem of Attribution' (2012) 17 (2) Journal of Conflict and Security Law 23; Gary Brown and Keira Poellet, ‘The Customary International Law of Cyberspace’ (2012) Strategic Studies Quarterly 137.
  106. Dan Efrony and Yuval Shany, ‘A Rule Book on the Shelf? Tallinn Manual 2.0 on Cyberoperations and Subsequent State Practice’ (2018) 112 AJIL 583, 638.
  107. French Ministry of the Armies, ‘International Law Applied to Operations in Cyberspace’, 9 September 2019, at p. 7, stating that ‘France does not rule out the possibility that a cyberoperation without physical effects may also be characterised as a use of force’.
  108. Dutch Ministry of Foreign Affairs, ‘Letter to the parliament on the international legal order in cyberspace’ (5 July 2019) at p. 4, stating that ‘in the view of the government, at this time it cannot be ruled out that a cyber operation with a very serious financial or economic impact may qualify as the use of force’.
  109. Dutch Ministry of Foreign Affairs, ‘Letter to the parliament on the international legal order in cyberspace’ (5 July 2019) at p. 4.
  110. French Ministry of the Armies, ‘International Law Applied to Operations in Cyberspace’, 9 September 2019, at p. 7.
  111. Tallinn Manual 2.0, commentary to rule 69, para 9.
  112. Cf. US, State Department Legal Advisor Brian Egan, International Law and Stability in Cyberspace, Speech at Berkeley Law School (10 November 2016), 13 (“In certain circumstances, one State’s non-consensual cyber operation in another State’s territory could violate international law, even if it falls below the threshold of a use of force.”) (emphasis original); UK, Attorney General Jeremy Wright QC MP, Cyber and International Law in the 21st Century, Speech (23 May 2018) (“In certain circumstances, cyber operations which do not meet the threshold of the use of force but are undertaken by one state against the territory of another state without that state’s consent will be considered a breach of international law.”).
  113. Tallinn Manual 2.0, commentary to rule 69, para 9 (a).
  114. Tallinn Manual 2.0, commentary to rule 69, para 9 (d).
  115. Tallinn Manual 2.0, commentary to rule 69, para 9 (f).
  116. Oil Platforms (Islamic Republic of Iran v United States of America) (Judgment) 2003 ICJ Rep 161, para 72.
  117. Military and Paramilitary Activities in and against Nicaragua (Nicaragua v United States of America) (Merits) [1986] ICJ Rep 14, para 95.
  118. Tallinn Manual 2.0, commentary to rule 71, para 8.
  119. ILC Articles on State Responsibility, Commentary, part 3 ch 2 at para 1.
  120. Austria, Pre-Draft Report of the OEWG - ICT: Comments by Austria (31 March 2020), stating that ‘a violation of the principle of State sovereignty constitutes an internationally wrongful act – if attributable to a State – for which a target State may seek reparation under the law of State responsibility. A target State may also react through proportionate countermeasures.’ (emphasis added).
  121. Estonia, ‘President of the Republic at the opening of CyCon 2019’ (29 May 2019), stating that “states have the right to react to malicious cyber operations, including using diplomatic response but also countermeasures”
  122. French Ministry of the Armies, ‘International Law Applied to Operations in Cyberspace’ (9 September 2019) 6, stating that ‘In response to a cyberattack, France may consider diplomatic responses to certain incidents, countermeasures, or even coercive action by the armed forces if an attack constitutes armed aggression.’
  123. Germany, ‘Statement by Ambassador Dr Thomas Fitschen, Director for the United Nations, Cyber Foreign Policy and Counter-Terrorism, Federal Foreign Office of Germany’ (November 2018) 3, stating that ‘in case of a cyber operation that is in breach of an international legal obligation below the level of the use or threat of force prohibited by Art. 2 (IV) [of the UN Charter] States are also entitled to take countermeasures as allowed by international law.’
  124. Japan, ‘Japan’s Position Paper for the Report of the United Nations Open-Ended Working Group on “Developments in the Field of Information and Telecommunications in the Context of International Security”’ (undated), stating that ‘Japan recognizes that basic rules on State responsibility including those on countermeasures applies to cyberspace.’
  125. Dutch Ministry of Foreign Affairs, ‘Letter to the parliament on the international legal order in cyberspace’ (5 July 2019) 7.
  126. United Kingdom, ‘Statement on Other Disarmament Measures and International Security to the 72nd UNGA First Committee’ (23 October 2017), stating that ‘We reaffirm that the law of state responsibility applies to cyber operations in peacetime, including the availability of the doctrine of countermeasures in response to internationally wrongful acts.’
  127. Brian J. Egan, ‘Remarks on International Law and Stability in Cyberspace’ (10 November 2016), stating that countermeasures are available ‘to address malicious cyber activity’ if that activity amounts to a prior internationally wrongful act attributable to another State.
  128. Brazil, ‘Open-ended Working Group on developments in the field of information and telecommunications in the context of international security: Second Substantive Session - New York, 11 February 2020: Statement by the Delegation of Brazil’ (11 February 2020), stating that ‘In the case of malicious acts in cyberspace, it is often difficult to attribute responsibility to a particular State or actor with unqualified certainty. A decision to resort to countermeasures in response to such acts carries a high risk of targeting innocent actors, and of triggering escalation.’
  129. China, ‘Statement by the Chinese Delegation at the Thematic Debate of the First Committee of the 72th UNGA’ (October 2017), stating that ‘Countries should discuss application of international law in the manner conducive to maintain peace, avoid introducing force, deterrence and countermeasures into cyberspace, so as to prevent arms race in cyberspace and reduce risks of confrontation and conflicts.’
  130. Cuba, ‘Declaration by Miguel Rodríguez, Representative of Cuba, at the Final Session of Group of Governmental Experts on Developments in the Field of Information and Telecommunications in the Context of International Security’ (23 June 2017), registering ‘serious concern over the pretension of some, reflected in paragraph 34 of the draft final report, to convert cyberspace into a theater of military operations and to legitimize, in that context, unilateral punitive force actions, including the application of sanctions and even military action by States claiming to be victims of illicit uses of ICTs.’ (emphasis added).
  131. ILC Articles on State Responsibility, Art 49(1); Case Concerning the Gabčíkovo-Nagymaros Project (Hungary/Slovakia) (Judgment) [1997] ICJ Rep 7, para 83.
  132. ILC Articles on State Responsibility, Art 52(3) – 52(4).
  133. ILC Articles on State Responsibility, Art 52(1)(a). According to the UK Attorney General, the UK does not feel legally obliged, when taking countermeasures in response to a covert cyber intrusion, to “give prior notification to the hostile state”. UK Attorney General, Jeremy Wright QC MP, ‘Cyber and International Law in the 21st Century’.
  134. ILC Articles on State Responsibility, Art 28-41; the list of consequences includes (i) continued duty of performance, (ii) cessation and non-repetition, (iii) reparation, and (iv) particular consequences of a serious breach of obligations under peremptory norms of general international law.
  135. ILC Articles on State Responsibility, Art 52(1)(b) – 52(2).
  136. ILC Articles on State Responsibility, Art 49(1); Case Concerning the Gabčíkovo-Nagymaros Project (Hungary/Slovakia) (Judgment) [1997] ICJ Rep 7, para 87. The list of consequences in Art 28-41 includes (i) continued duty of performance, (ii) cessation and non-repetition, (iii) reparation, and (iv) particular consequences of a serious breach of obligations under peremptory norms of general international law.
  137. ILC Articles on State Responsibility, Art 49(3).
  138. Such as the obligation to refrain from the threat or use of force as embodied in the UN Charter, obligations for the protection of fundamental human rights, and obligations of a humanitarian character prohibiting reprisals. ILC Articles on State Responsibility, Art 50(1).
  139. ILC Articles on State Responsibility, Art 50(2).
  140. Articles on State Responsibility, Art 51; Case Concerning the Gabčíkovo-Nagymaros Project (Hungary/Slovakia) (Judgment) [1997] ICJ Rep 7, para 85.
  141. ILC Articles on State Responsibility, Art 54.
  142. President of Estonia, Kersti Kaljulaid, ‘President of the Republic at the opening of CyCon 2019’ (29.05.2019).
  143. Michael N Schmitt, ‘Estonia Speaks Out on Key Rules for Cyberspace’ Just Security (10.06.2019), considering the Estonian interpretation to be “an advantageous development in the catalogue of response options that international law provides to deal with unlawful acts”.
  144. French Ministry of the Armies, International Law Applied to Operations in Cyberspace, p. 10, arguing that collective countermeasures are not authorised under international law.
  145. Jeff Kosseff, ‘Collective Countermeasures in Cyberspace,’ (2020) Notre Dame Journal of International & Comparative Law Vol. 10, Iss. 1, 34; François Delerue, Cyber Operations and International Law (CUP 2020), 457.
  146. ILC Articles on State Responsibility, Commentary in Part 3, Chapter 2 on Art 49, para 3.
  147. ILC Articles on State Responsibility, Commentary to Part One, Chapter 5, para 8 (noting that “[i]n a bilateral dispute over State responsibility, the onus of establishing responsibility lies in principle on the claimant State”).
  148. See, eg, Trail Smelter case (United States v Canada) (Award) (1941) 3 RIAA 1905, 1965; see also Robin Geiss and Henning Lahmann, ‘Freedom and Security in Cyberspace: Shifting the Focus Away from Military Responses Towards Non-Forcible Countermeasures and Collective Threat-Prevention’ in Katharina Ziolkowski (ed), Peacetime Regime for State Activities in Cyberspace (NATO CCD COE 2013) 624 (noting that in cases where State responsibility is involved, the required threshold tends to shift towards ‘clear and convincing’”).
  149. James Green, ‘Fluctuating Evidentiary Standards for Self-Defence in the International Court of Justice’ (2009) 58 ICLQ 163, 167 (emphasis original).
  150. ILC Articles on State Responsibility, Commentary in Part 3, Chapter 2 on Art 49, para 3.
  151. Case Concerning the Gabčíkovo-Nagymaros Project (Hungary/Slovakia) (Judgment) [1997] ICJ Rep 7; Gary Corn and Eric T Jensen, ‘The Use of Force and Cyber Countermeasures’ (2018) 32 Temple International & Comparative Law Journal 127; Michael Schmitt ‘Below the Threshold Cyber Operations: The Countermeasures Response Option and International Law’ (2014) 54 Virginia Journal of International Law 697, 715.
  152. See, Case Concerning the Gabčíkovo-Nagymaros Project (Hungary/Slovakia) (Judgment) [1997] ICJ Rep 7, para 84 (“…the injured State must have called upon the State committing the wrongful act to discontinue its wrongful conduct”).
  153. Gary Corn and Eric T Jensen, ‘The Use of Force and Cyber Countermeasures’ (2018) 32 Temple International & Comparative Law Journal 127.
  154. UK Attorney General, Jeremy Wright QC MP, ‘Cyber and International Law in the 21st Century’.
  155. ILC Articles on State Responsibility, Article 52(2); Michael Schmitt ‘Below the Threshold Cyber Operations: The Countermeasures Response Option and International Law’ (2014) 54 Virginia Journal of International Law 697.
  156. Case Concerning the Gabčíkovo-Nagymaros Project (Hungary/Slovakia) (Judgment) [1997] ICJ Rep 7, para 85; see also Michael Schmitt ‘Below the Threshold Cyber Operations: The Countermeasures Response Option and International Law’ (2014) 54 Virginia Journal of International Law 697, 723 “A countermeasure that is disproportionate to the injury suffered amounts to punishment or reprisal and is therefore contrary to the object and purpose of the law governing countermeasures. Consequently, its wrongfulness is not precluded”.
  157. ILC Articles on State Responsibility, Article 51.
  158. ILC Articles on State Responsibility, Article 51, para 1.
  159. Air Service Agreement, para. 83; see also ILC Articles on State Responsibility, Article 51, para 3.
  160. ILC Articles on State Responsibility, Article 49(1).
  161. ILC Articles on State Responsibility, Article 49(3).
  162. Robin Geiss and Henning Lahmann, ‘Freedom and Security in Cyberspace: Shifting the Focus Away from Military Responses Towards Non-Forcible Countermeasures and Collective Threat-Prevention’ in Katharina Ziolkowski (ed), Peacetime Regime for State Activities in Cyberspace (NATO CCD COE 2013); see also Case Concerning the Gabčíkovo-Nagymaros Project (Hungary/Slovakia) (Judgment) [1997] ICJ Rep 7, para 87.
  163. Michael Schmitt ‘Below the Threshold Cyber Operations: The Countermeasures Response Option and International Law’ (2014) 54 Virginia Journal of International Law 697, 714.

4.3 Bibliography and further reading[edit | edit source]

  • Russell Buchan ‘Cyber Attacks: Unlawful Uses of Force or Prohibited Interventions?’ (2012) 17 Journal of Conflict and Security Law 212.
  • Gary Corn and Eric T Jensen, ‘The Use of Force and Cyber Countermeasures’ (2018) 32 Temple International & Comparative Law Journal 127.
  • Robin Geiss and Henning Lahmann, ‘Freedom and Security in Cyberspace: Shifting the Focus Away from Military Responses Towards Non-Forcible Countermeasures and Collective Threat-Prevention’ in Katharina Ziolkowski (ed), Peacetime Regime for State Activities in Cyberspace (NATO CCD COE 2013).
  • Terry D Gill, ‘Non-intervention in the Cyber Context’ in Katharina Ziolkowski (ed), Peacetime Regime for State Activities in Cyberspace (NATO CCD COE 2013).
  • Wolff Heintschel von Heinegg, ‘Warships’ (2015) in Rüdiger Wolfrum (ed) Max Planck Encyclopedia of Public International Law (OUP 2008-, updated October 2015).
  • Albert J Hoffmann, ‘Freedom of Navigation’ in Rüdiger Wolfrum (ed) Max Planck Encyclopedia of Public International Law (OUP 2008-, updated April 2011).
  • M Jamnejad and M Wood, ‘Prohibition of Intervention’ (2009) 22 Leiden Journal of International Law 345.
  • Natalie Klein, Maritime Security and the Law of the Sea (OUP 2012).
  • Doris König, ‘Flag of Ships’ in Rüdiger Wolfrum (ed) Max Planck Encyclopedia of Public International Law (OUP 2008-, updated April 2009).
  • Philip Kunig, ‘Prohibition of Intervention’, in Rüdiger Wolfrum (ed) Max Planck Encyclopedia of Public International Law (OUP 2008-, updated April 2008).
  • Patricia Kwast, ‘Maritime Law Enforcement and the Use of Force: Reflections on the Categorisation of Forcible Action at Sea in the Light of the Guyana/Suriname Award’ (2008) 13 Journal of Conflict and Security Law.
  • Michael N Schmitt ‘Below the Threshold Cyber Operations: The Countermeasures Response Option and International Law’ (2014) 54 Virginia Journal of International Law 697.
  • Michael N Schmitt, ‘Computer Network Attack and Use of Force in International Law: Thoughts on a Normative Framework’ 37 Columbia Journal of Transnational Law (1999) 885.
  • Katja Ziegler, ‘Domaine Réservé’, in Rüdiger Wolfrum (ed) Max Planck Encyclopedia of Public International Law (OUP 2008-, updated April 2013).

4.4 Contributions[edit | edit source]

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