1. Introduction
Several recent armed conflicts, including Russia-Ukraine and Israel-Hamas, have received global attention. While the main military confrontations have occurred on land, the two conflicts have also involved naval action, such as armed clashes in the Black Sea and the Israeli blockade of the Gaza Strip. These events indicate that the law of armed conflict in the maritime domain, namely, the law of naval warfare,Footnote 1 remains important and deserving of analysis. However, compared to the law of armed conflict on land,Footnote 2 the law of naval warfare has been scarcely examined in existing literature.
One of the challenges in analysing the law of naval warfare is the lack of new treaties. Since the adoption of the several Hague Conventions in 1899 and 1907Footnote 3 and the Second Geneva Convention in 1949,Footnote 4 no treaty primarily addressing the law of naval warfare has been adopted, while the law of armed conflict on land has been updated by several treaties, such as the two Additional Protocols to the Geneva Convention in 1977,Footnote 5 as well as treaties prohibiting the use of certain weapons, such as land mines.Footnote 6 Partly as a result of this lack of treaties, most rules of the law of naval warfare derive from customary international law.Footnote 7 A consequence of this is that the law of naval warfare remains somewhat unclear, not having been codified in a treaty. Since the Second World War, many new weapons have been developed, and the United Nations Convention on the Law of the Sea (UNCLOS)Footnote 8 which dramatically changed peacetime law in the maritime domain,Footnote 9 was adopted in 1982. These facts may have resulted in changes in State practice, which could constitute the customary rules of naval warfare, but these rules remain uncertain.
To overcome this lack of clarity, international military manuals have been created that are designed to reflect the existing rules of customary international law. With regard to naval warfare, two manuals have been published: the San Remo Manual on International Law Applicable to Armed Conflicts (San Remo Manual)Footnote 10 in 1994 and the Newport Manual on the Law of Naval Warfare (Newport Manual)Footnote 11 in 2023. However, while the two manuals overlap in scope, they differ regarding the impact of UNCLOS during armed conflict. While the San Remo Manual accommodates UNCLOS, the Newport Manual states that where there are inconsistencies, the law of naval warfare prevails over UNCLOS during times of armed conflict. In particular, while the San Remo Manual requests that belligerent parties pay due regard to the rights and obligations of coastal States over their exclusive economic zones (EEZ),Footnote 12 the Newport Manual says that the law of naval warfare divides the ocean into two spaces: first, neutral sea areas, i.e. the internal waters, archipelagic waters and territorial sea of neutral States, where those States have sovereignty; and, second, areas where belligerent rights may be exercised, which includes all waters beyond neutral sea areas under the sovereignty of coastal States, including those of neutral States.Footnote 13 The Newport Manual does not require that belligerent parties pay due regard to the rights and obligations of other States in their EEZ, where coastal States only possess sovereign rights and jurisdiction, rather than sovereignty.Footnote 14 Moreover, as will be explored in Section 3.1.2 below, according to the Newport Manual, due regard is a peacetime concept that is not applicable during armed conflict.Footnote 15 Such divergence of views concerning the applicability of the due regard obligation has also been apparent during the process of updating the San Remo Manual, which started in 2019.Footnote 16
Against this background, this article attempts to clarify the impact of UNCLOS during armed conflict, especially in relation to the rights of neutral coastal States in their EEZ. The reason for focusing on neutral States is that there seems to be a shared understanding that the EEZ of belligerent coastal States can be used as a battlefield.Footnote 17 To elaborate on this further, Section 2 examines the relationship between UNCLOS and the law of naval warfare. Section 3 examines both the San Remo Manual and the Newport Manual as well as State military manuals. Finally, Section 4 analyses the applicability of the obligation of due regard during armed conflict. Section 5 follows with a conclusion.
2. The relationship between the law of the sea and the law of naval warfare
2.1. Application of UNCLOS during armed conflict
Since the formal division of the laws applicable to peace and war in the nineteenth century, it has been considered that the occurrence of an armed conflict does not automatically terminate a treaty.Footnote 18 Whether a treaty is terminated, suspended or continues to apply during armed conflict must be carefully examined under the rules of international law. For this purpose, the International Law Commission (ILC) created the Draft Articles on the Effects of Armed Conflicts on Treaties (ILC Draft Articles) in 2011.Footnote 19 According to Article 4 ILC Draft Articles, where a treaty contains provisions concerning its operation during armed conflict, these provisions apply.Footnote 20 Therefore, whether UNCLOS applies during armed conflict is to be determined in the first instance by the text itself.
UNCLOS does not contain provisions which expressly refer to armed conflict. However, the preamble hints at the scope of the treaty’s application during armed conflict, noting that the States Parties affirm ‘that matters not regulated by this Convention continue to be governed by the rules and principles of general international law’.Footnote 21 Thus while armed conflict itself is regulated by rules outside UNCLOS, the provisions of UNCLOS themselves remain applicable during armed conflict along with the law of naval warfare.
Article 298(1)(b) UNCLOS can be used to support the assertion of the treaty’s continued applicability during armed conflict. It allows States to opt out of the compulsory dispute settlement UNCLOS provides for in ‘disputes concerning military activities, including military activities by government vessels and aircraft engaged in non-commercial service’.Footnote 22 This explicit provision allowing States to exclude ‘military activities’ from dispute settlement implies that such activities would otherwise fall within the substantive scope of UNCLOS, potentially including military operations during armed conflict at sea. In other words, the existence of the opt-out suggests that UNCLOS provisions (e.g. on freedom of navigation, EEZ rights, etc) apply even when military force is used. This provision may be interpreted broadly to include wartime naval operations, meaning that unless a State makes the Article 298(1)(b) declaration, an UNCLOS tribunal could in theory assess the legality of wartime actions, thus providing a concrete example of the applicability of UNCLOS rules during armed conflict. However, a narrow reading of the provision might interpret ‘military activities’ to mean only those conducted during peacetime, e.g. exercises or reconnaissance, which would suggest UNCLOS does not regulate or apply to wartime hostilities, which would thus fall entirely under the law of naval warfare. Whilst this latter interpretation is unconvincing given there is no reason to exclude hostile activities from the scope of Article 298(1)(b), the fact that the article is not clear on whether ‘military activities’ refers to wartime or peacetime actions means it does not decisively indicate whether UNCLOS applies during armed conflict. Such lack of clarity highlights the treaty’s silence on the matter and the resulting uncertainty about its interaction with the law of naval warfare.
In such cases, the ILC Draft Articles have two provisions governing whether a treaty is terminated or continues to apply during armed conflict. According to Article 6(a), ‘the nature of the treaty, in particular its subject matter …’ is important in deciding the impact of armed conflict on the treaty. Based on this provision, Article 7 and the Annex provide an indicative list of the subject-matters of treaties that are expected to continue to apply during armed conflict. Noting the nature of UNCLOS as the key treaty governing the law of the sea, it also contains relevant subject matter.Footnote 23 Several of its provisions could be categorised as such according to the Annex of the ILC Draft Articles, namely: treaties establishing maritime delimitation (paragraph (a)); law-making treaties (paragraph (c)); treaties related to environmental protection (paragraph (g)); treaties to establish international organisations (paragraph (j)); and treaties for dispute settlement (paragraph (k)). Thus, if applicable, the ILC Draft Articles confirm that UNCLOS should continue to apply during armed conflict.
2.2. Law of naval warfare as lex specialis
Although it is clear that UNCLOS remains generally applicable during armed conflict, given that it does not contain provisions regarding hostile activities it cannot comprehensively regulate armed conflicts at sea. As Wilson and Kraska have aptly pointed out, UNCLOS is not intended to replace the existing rules of naval warfare,Footnote 24 it is predominantly the customary rules of the law of naval warfare that should regulate naval warfare. However, there is potential for conflict between the two regimes. For example, under the flag State principle in UNCLOS, non-flag States are not allowed to visit foreign vessels on the high seas except in certain limited situations.Footnote 25 In contrast, the law of naval warfare allows belligerent parties to visit foreign merchant vessels to verify enemy characterFootnote 26 and, under specific conditions, they are even allowed to attack those vessels.Footnote 27
The notion of lex specialis as a method to resolve such discrepancies has been discussed since the era of Hugo Grotius.Footnote 28 The issue of determining priority of legal regimes has been grappled with by international courts since their inception. For example, in the Mavrommatis case, the Permanent Court of International Justice (PCIJ) considered the relationship between the Covenant of the League of Nations and Protocol XII to the Lausanne Treaty, and concluded that the latter prevailed.Footnote 29 Although the PCIJ did not explicitly state as much, it appears to have relied on two legal maxims: lex posterior derogate lege priori (a later law repeals an earlier law); and lex specialis derogat legi generali (special law repeals general laws) (lex specialis principle).Footnote 30
The function of the lex specialis principle in international law was developed by the International Court of Justice (ICJ) in its advisory opinion on Legality of the Threat or Use of Nuclear Weapons, which examined the relationship between the law of armed conflict and international human rights law. According to the ICJ, ‘what is an arbitrary deprivation of life’, as prohibited by Article 6 of the International Covenant on Civil and Political Rights (ICCPR), is determined by the law of armed conflict.Footnote 31 This assertion was based on two propositions: first, the law of armed conflict was considered lex specialis via-à-vis international human rights law; and, second, lex specialis takes priority over general law.Footnote 32 The law of armed conflict is considered to be lex specialis.Footnote 33 The law of naval warfare is applicable only during armed conflict and is a part of the law of armed conflict. As such, the law of naval warfare is lex specialis vis-à-vis UNCLOS during armed conflict. During the drafting process of the San Remo Manual, experts shared the view that the law of armed conflict is lex specialis via-à-vis the rules of UNCLOS that may have an application during armed conflict.Footnote 34 Furthermore, the Newport Manual states that the law of naval warfare is lex specialis and, consequently, prevails over the law of the sea where there is a conflict between their relevant provisions.Footnote 35
Hence, to clarify the impact of UNCLOS as lex generalis during armed conflict, the function of the lex specialis principle must be identified. Under modern international law, the principle is used to solve the conflict of norms, by prioritising and/or making lex specialis ‘prevail’Footnote 36 over lex generalis.Footnote 37 On this point, paragraph 8 of the ILC’s Conclusions of the Work of the Study Group on the Fragmentation of International Law provides that ‘[m]ost of international law is dispositive. This means that special law may be used to apply, clarify, update or modify, as well as set aside, general law’.Footnote 38 Therefore, to identify the function of the principle for the relationship between UNCLOS and the law of naval warfare, the contents of the two bodies must be thoroughly verified and evaluated.
3. Neutral coastal States’ EEZ under the law of naval warfare
With regard to the neutrality of naval warfare, the Hague Convention XIII provides the relevant rules. Article 1 provides that ‘the Belligerents are bound to respect the sovereign rights of neutral Powers’.Footnote 39 As it uses the term ‘sovereign rights’, some States claimed during the Third UN Conference on the Law of the Sea that the newly introduced EEZ, an area in which coastal States enjoy sovereign rights, should be regarded as neutral waters and, therefore, hostile activities are prohibited within the EEZ.Footnote 40 However, because the coastal State’s rights in the EEZ are limited to economic matters, such as the exploration and exploitation of natural resources under UNCLOS, such arguments are no longer widely accepted. Therefore, based on the premise that belligerents may use the EEZ of neutral States (i.e. that an EEZ does not constitute part of the neutral waters of a coastal State), this section explores the constraints imposed on belligerents in the EEZs of neutral States by examining both the two key international military manualsFootnote 41 and national military manuals.Footnote 42
3.1. Different approaches in the two international manuals
3.1.1. San Remo Manual
The San Remo Manual was drafted between 1988 and 1994 by a group of legal and naval experts who participated in a series of roundtables organised by the International Institute of Humanitarian Law, founded in 1970 in San Remo. The manual aims to provide a current restatement of international law (lex lata) that applies to armed conflicts at sea. The manual also contains a few sections that can be regarded as progressive developments in the law (lex ferenda).Footnote 43
The San Remo Manual clearly respects the provisions of UNCLOS. According to paragraph 12 regarding the EEZ, ‘belligerents shall have due regard for the legitimate rights and duties of those neutral States’.Footnote 44 The wording of this rule derives from Article 58(3) UNCLOS, which obliges non-coastal States to have due regard for the rights and duties of coastal States. More concretely, paragraph 34 of the San Remo Manual provides that even when hostile actions are conducted, belligerent parties shall have due regard for the rights of coastal States, especially for maritime structures over which coastal States are authorised to exercise jurisdiction (which is governed by Article 60 UNCLOS).
Although the due regard obligation is incorporated into the San Remo Manual,Footnote 45 one participant in the drafting process commented that this obligation would be mere lip service without further clarification.Footnote 46 In response to this concern, paragraph 35 imposes more concrete obligations on belligerents by stipulating that:
If a belligerent considers it necessary to lay mines in the exclusive economic zone or the continental shelf of a neutral State, the belligerent shall notify that State, and shall ensure, inter alia, that the size of the minefield and the type of mines used do not endanger artificial islands, installations and structures, nor interfere with access thereto, and shall avoid so far as practicable interference with the exploration or exploitation of the zone by the neutral State.Footnote 47
Mines can remain even after armed conflicts have finished and could therefore cause long term damage to the economic activities of coastal States. If coastal States know where they have been set, they will be able to dramatically decrease the potential for damage by those mines.Footnote 48 This provision is thus highly valued by coastal States. Meanwhile, Article 3 Hague Convention VIII requires the belligerents to make an effort to notify the danger zones to all States (not limited to the coastal States of the EEZ) ‘as soon as military exigencies permit’.Footnote 49 In other words, Hague VIII provides that ‘military exigencies’ may provide a justification for delay in notification, whereas the San Remo Manual regards notification as an absolute duty.Footnote 50 Given the vastness of the area covered by an EEZ and the importance of information on laying mines,Footnote 51 these duties on belligerents appear burdensome for their hostile activities because of the risk of enemy States obtaining information on their mine strategies.
3.1.2. Newport Manual
Since the adoption of the San Remo Manual, several important technologies, such as cyberweapons and unmanned vehicles, have been developed. The process for developing the San Remo Manual 2.0 is thus ongoing, but some members of the expert group were dissatisfied with the slow pace of the process. Consequently, they withdrew from the San Remo process to create an independent document, the Newport Manual,Footnote 52 under the initiative of the United States (US) Naval War College at Newport, Rhode Island. Unlike the San Remo Manual, which also includes some rules lex ferenda, the Newport Manual focuses solely on codifying lex lata. For this purpose, the contributors to the Newport Manual looked to State practice and opinio juris and collected those practices and lessons to influence future planning and operations.Footnote 53
According to Section 4.1 of the Newport Manual, while the territorial seas of neutral States are categorised as neutral seas where belligerent rights may not be exercised, the EEZ of neutral States does not fall within the scope of neutral waters.Footnote 54 Section 4.1.2.1 provides the rules for the Contiguous Zone, EEZ and Continental Shelf.Footnote 55 The first footnote of this section, footnote 323, notes the position taken by the San Remo Manual on these matters, and that the latter is not supported by international law:
The San Remo Manual suggests that belligerents shall have due regard for the resource rights of the neutral State when conducting hostilities in the EEZ or on the continental shelf. If a belligerent lays mines in a neutral State’s EEZ or continental shelf, the San Remo Manual also requires it to notify the neutral State, as well as ensure that the size of the minefield and the types of mines employed do not interfere with the neutral State’s resource rights. Belligerents shall additionally have due regard for the protection and preservation of the marine environment. These requirements of the San Remo Manual are a scholarly expression of progressive development of the law. This lex ferenda view is not formative of international law and it does not reflect the law of naval warfare as a lex specialis regime that displaces the law of the sea if the latter is inconsistent with the former.Footnote 56
The last paragraph of the Newport Manual section on the rules applicable beyond waters under the sovereignty of the coastal State concludes that:
The coastal State authority in the EEZ and on the continental shelf is without prejudice to the lex specialis of the law of naval warfare during armed conflict at sea. When conducting military operations in the EEZ and on the continental shelf, belligerents shall, consistent with military necessity and operational requirements, respect the rights and duties of neutral States.Footnote 57
This paragraph is somewhat ambiguous because its first sentence could be read to mean that neutral coastal States’ rights in the EEZ and continental shelf do not constrain belligerents during armed conflict, which seems inconsistent with the second sentence that could be interpreted as requiring belligerents to respect the rights of neutral coastal States. This apparent tension is compounded by footnote 323, which suggests that treating coastal States’ rights as protected during naval warfare reflects lex ferenda, not what the law actually is. However, footnote 329, which is added in the second sentence of the above paragraph, is helpful in clarifying its meaning. Footnote 329 notes that some national manuals provide for due regard of neutral coastal States’ rights, but that this is ‘the peacetime standard of “due regard”, which is not applicable during times of armed conflict’.Footnote 58 As the Newport Manual takes the position that a State manual cannot replace a meaningful assessment of operational State practice when determining the latter for the purposes of the customary rules of naval warfare,Footnote 59 footnote 323 could be taken to indicate that there is insufficient evidence of State practice in the form of actual military operations to support the idea that due regard is paid to coastal States’ rights over the EEZ. It could also be interpreted to mean that the content of the ‘due regard’ principle may be different in times of armed conflict, which reflects the approach to the relationship of international humanitarian law and international human rights law, where the interpretation of the latter is influenced by the former when it is applicable. However, given that the Newport Manual explicitly states that due regard is a peacetime concept, it is difficult to conclude that it envisages an armed conflict version of the principle, albeit with a different scope. It can thus be concluded that the reference to ‘neutral States’ in the last sentence of the above quotation from the Newport Manual ought instead to be to ‘flag States’, as it refers to flag States whose vessels are not party to the conflict and does not include the coastal State to which the EEZ belongs.
3.2. State manuals
As the Newport Manual indicates, the domestic military manual of a State cannot simply be considered as State practice that contributes to establishing customary rules. The status of these manuals may differ from State to State, and the expressions used in the manuals may also be relevant. Therefore, it is essential to examine each manual individually and consider the extent to which they are used for the formulation of customary rules. That said, it is also true that there is limited actual State practice in relation to hostile activities and, accordingly, the military manuals that the military of each State is expected to follow can have some relevance for formulating customary rules of the law of armed conflict.Footnote 60
In relation to the rights and duties of neutral coastal States within their EEZs, the Newport Manual appears to rely heavily on the US position, which does not recognise such rights during armed conflict. Even though the US is not a party to UNCLOS, section 7.3.8 of the Commander’s Handbook on the Law of Naval Operations,Footnote 61 which provides the rules applicable in the EEZs of neutral States, acknowledges the EEZ regime as provided in UNCLOS as customary international law.Footnote 62 However, this is followed by the assertion that ‘(a) neutral State’s EEZ is not neutral waters and coastal State rights and jurisdiction in the EEZ established in UNCLOS do not modify the law of naval warfare. Belligerents may conduct hostilities in a neutral State’s EEZ’.Footnote 63 As a result, there is also no provision relating to duties regarding naval mines within neutral States’ EEZs, such as that provided in paragraph 35 of the San Remo Manual.
Other States’ manuals,Footnote 64 such as those of Australia,Footnote 65 Canada,Footnote 66 Denmark,Footnote 67 France,Footnote 68 Germany,Footnote 69 New Zealand,Footnote 70 Norway,Footnote 71 SpainFootnote 72 and the United Kingdom (UK),Footnote 73 provide for the rights and duties of neutral coastal States over their EEZs (see Table 1).Footnote 74 Although most of them appear to be influenced by the San Remo Manual, some differences exist. The Canadian manual incorporates the San Remo Manual, and its content is almost identical to that of the San Remo Manual. There are three main differences among the other manuals.Footnote 75
Table 1. Overview of States’ Manuals
O: contains such rights and obligations, X: does not contain such rights and obligations, ▲: not clear
First, the French and Spanish manuals do not use the term ‘due regard’. These two manuals are written in French and Spanish, both of which are authentic languages of UNCLOS as per Article 320. According to the text of these two languages, ‘due regard’ is ‘dûment compte’ in French and ‘debidamente en cuenta’ in Spanish. However, these expressions are not used to describe the rules regarding the EEZ in their respective manuals. Instead, the two manuals use the simpler expression ‘to take into account’ (‘tenir compte’ in French and ‘tener en cuenta’ in Spanish), in respect of the duties and rights of coastal States in their EEZ.Footnote 76 This might indicate that these States’ manuals consider that the standard of due regard vis-à-vis the rights of coastal States’ rights regarding their EEZs differs in peacetime under UNCLOS from that applicable in wartime under the law of naval warfare.Footnote 77
Second, most manuals do not reflect the mining obligations provided in paragraph 35 of the San Remo Manual. While the manuals of SpainFootnote 78 and New ZealandFootnote 79 both incorporate paragraph 35 of the San Remo Manual, those of AustraliaFootnote 80 and the UKFootnote 81 simply provide for due regard to be paid to legitimate uses by other States in general, and not particularly to coastal States in relation to their EEZ.Footnote 82 Denmark and Norway find a middle ground with their manuals saying that due regard should be paid;Footnote 83 simultaneously, they request that notification of laying mines be given to neutral coastal States, but other obligations, including the obligation not to endanger marine structures, are not included. This might indicate that the full text of paragraph 35 is unacceptable for these States, even though they accept the applicability of due regard obligations for coastal States’ rights regarding their EEZs.
Third, while the San Remo Manual uses the auxiliary verb ‘shall’, which implies legal obligations, some manuals do not use it in certain contexts. For example, the Australian manual, which incorporates the EEZ into the meaning of ‘international waters’ together with the high seas, states that ‘(w)here mines are laid in international waters, belligerents should pay due regard’.Footnote 84 Given that the manual also uses the term ‘shall’ in different contexts, this usage of ‘should’ may indicate the Australian understanding that this is not a legal obligation.Footnote 85
4. Incorporation of the law of naval warfare into UNCLOS through the due regard obligation
As shown in Section 2, while the law of naval warfare is lex specialis vis-à-vis conflicting provisions of UNCLOS, many States (at least in military manuals) respect the rights and duties of coastal States regarding their EEZs, which are based on UNCLOS. Accordingly, the rights and duties that States enjoy under UNCLOS should ‘continue to exist, with minor exceptions, during armed conflict’.Footnote 86 However, because the law of naval warfare is applied as lex specialis, the extent to which rights and obligations under UNCLOS prevail during armed conflicts depends on the relationship between these two legal regimes. This section elaborates on this relationship.
4.1. Function of lex specialis
The lex specialis principle may operate in various ways. As shown in Section 2, according to the ILC, lex specialis is used ‘to apply, clarify, update or modify, as well as, set aside’ lege generali.Footnote 87 Based on this classification, the US expects the law of naval warfare (lex specialis) to set aside conflicting provisions of the law of the sea (legi generali), especially coastal States’ rights regarding their EEZs and due regard obligations under general law.Footnote 88 However, if States consider that coastal States may have some rights regarding their EEZs, the function of the lex specialis cannot be to set aside the EEZ rules under the law of the sea. Rather, it can be used to clarify or modify the general law (the law of the sea).
On this point, the chair of the ILC’s study group, Koskenniemi, carefully examined the nature of the incorporation of the standard of the law of armed conflict into the concept of ‘arbitrariness’ in Article 6 ICCPR by the ICJ in its advisory opinion on the Legality of the Threat or Use of Nuclear Weapons, discussed in Section 2.2.Footnote 89 While the outline of the study group, which was used for discussion in 2003, classified the ICJ’s remark as an elaboration or application of general law,Footnote 90 its preliminary report in 2004 classified it as an exception to the general rule.Footnote 91 However, the preliminary report also admitted that, even in the case of exception, the general law that is being set aside by lex specialis does not vanish but, rather, operates in parallel.Footnote 92 Therefore, irrespective of the different classifications of the study group, the ILC seems to take the position that the law of armed conflict, as lex specialis, can work to clarify or modify general law.
That said, this does not mean that the law of naval warfare always clarifies or modifies the law of the sea rather than setting it aside. One of the factors that led the ICJ to modify human rights law through the application of the law of armed conflict was the vagueness or flexibility of the term ‘arbitrarily’. The concept is so vague that it could have different meanings in peacetime as opposed to during times of armed conflict.Footnote 93 Therefore, if UNCLOS also has a concept equivalent to ‘arbitrarily’, it might be able to accommodate the law of naval warfare through that concept. On this point, as several States try to use the due regard obligation under UNCLOS during armed conflict, that concept merits further examination.
4.2. Flexibility of due regard
Under UNCLOS, the due regard obligation within EEZs operates in two opposing directions. As shown in Section 3.1.1, Article 58(3) requires non-coastal States to ‘have due regard to the rights and duties of coastal States’ but, in reverse Article 56(2) requires coastal States to ‘have due regard to the rights and duties of other States’. Therefore, both coastal and non-coastal States shall have reciprocal due regard for each other’s rights and duties, and due regard may work to balance the interests of the relevant States.Footnote 94 Because these provisions are not further refined in UNCLOS or other instruments, the meaning of due regard must be determined on a case-by-case basis.Footnote 95 Meanwhile, as these two provisions are not limited to the rights and duties which derive from UNCLOS, like Article 56(1)(c), the rights and duties in these two provisions may include other ‘legal rights as they otherwise arise as a matter of international law’.Footnote 96
Based on this understanding, in the Chagos Marine Protected Area Arbitration, the arbitral tribunal constituted under Annex VII concluded that the UK failed to have due regard to Mauritius’ rights and interests arising from the Lancaster House Undertakings,Footnote 97 even though it did not take the form of an official treaty. Furthermore, in the San Pedro Pio case brought before ITLOS, Switzerland claimed that Nigeria failed to pay due regard under Article 56(2) to its rights under the ICCPR.Footnote 98 Because of the removal of the case from the list before ITLOS rendered its judgment, this point was not decided. However, given the decision in the Chagos Marine Protected Area Arbitration and the literal interpretation of Article 56(2), which does not impose any limitation on the sources of rights, the interpretation by Switzerland sounds plausible to some extent. One possible rebuttal to its argument is that the ICCPR provides individual rights, rather than rights owed to States.
Certainly, there have not been any decisions to the effect that the rights protected by the due regard obligation may also be derived from customary international law. However, given that there is no restriction on the sources of rights, there are no grounds to exclude rights guaranteed under customary international law. Therefore, rights under the customary rules of the law of naval warfare fall to be considered within the context of the obligation to have due regard. As a result of paying due regard to these customary rights, coastal States need to respect belligerent rights, for example, to attack enemy vessels under Article 56(2) and, at the same time, belligerent parties may not destroy marine structures within an EEZ without any compelling reasons under Article 58(3). The concept of due regard can also be balanced in times of armed conflict, even though what will be required in the two situations is different.Footnote 99
4.3. Requirements of due regard in neutral coastal States’ EEZ
If the content of the due regard principle is different during armed conflict, it is essential to clarify what it contains. On this point, one attempt is paragraph 35 of the San Remo Manual, which provides that belligerents have several duties when they lay naval mines within the EEZs of neutral coastal States. However, given the non-acceptance of this rule by many States’ manuals, that clarification may not be regarded as reflecting the existing law of naval warfare. As the EEZ, which can extend up to 200 nautical miles, is much wider than a State’s territorial waters which only extend up to 12 nautical miles, and EEZs cover almost 36 per cent of the world’s oceans,Footnote 100 obligations of due regard owed to coastal States within their EEZs could easily be very burdensome for non-coastal belligerents.Footnote 101 However, coastal States now utilise their EEZ and continental shelf for purposes other than the traditional fishing and exploitation of hydrocarbon resources. For example, some European States, including Denmark, have established wind farm turbines within their EEZs.Footnote 102 Moreover, Norway has started carbon capture and storage (CCS) projects on its continental shelf.Footnote 103 By balancing these interests, due regard under the law of naval warfare within neutral States’ EEZs can be established.
That said, given the limited amount of State practice on this pointFootnote 104 and the improbability of a new treaty being concluded, both international and domestic manuals and academic teachings play a role in promoting such clarification and development. On this point, as discussed in the drafting process of the San Remo Manual, the values and principles of the law of armed conflict, like ‘military exigencies’, could serve as a guide.Footnote 105 Currently, there are some principles under the law of armed conflict, such as the principles of humanity, military necessity, distinction and proportionality,Footnote 106 that could assist in determining the scope of the due regard obligations during armed conflict. As examples of military activity within neutral coastal States’ EEZs, Ronzitti states that ‘belligerents are not allowed to destroy fixed platforms of a neutral State unless they become a base for hostile operations’.Footnote 107 Such an argument seems to derive from military necessity. Furthermore, Heinegg argues that if a choice between several military objects is possible in order to gain a comparable military advantage, the object whose damage could cause the most minor threat to those objects shall be chosen.Footnote 108 This argument seems to derive from the proportionality principle.
However, Heinegg also claims that the duty to pay due regard is ‘subject to considerations of military necessity’.Footnote 109 These scholarly arguments can be understood as follows: the principles of the law of naval warfare (military necessity and proportionality) simply displace due regard. Yet, because UNCLOS continues to apply during armed conflict, the principles of military necessity and proportionality do not displace due regard. Instead, they should be incorporated into the due regard obligation as a consequence of the modification of the rights and obligations under Articles 56(2) and 58(3) by the law of naval warfare, as lex specialis. The requirements of due regard during armed conflict should be informed by the rules of the law of naval warfare in a manner that balances military necessity and humanity.
In addition, thanks to their compulsory jurisdiction, UNCLOS tribunals may contribute to the development of the content of the principle of due regard in armed conflict. In fact, the principle of due regard in peacetime has been clarified and developed through case law.Footnote 110 If a State claims that another State fails to comply with its due regard obligation during armed conflict and thereby violates Article 56(2) or 58(3), such claims fall within the scope of the dispute settlement procedures set out in Part XV of UNCLOS, because they are categorised as disputes concerning the interpretation or application of UNCLOS, over which UNCLOS tribunals have compulsory jurisdiction under Article 286. Even though the tribunals may make a decision de facto based on the law of naval warfare, in accordance with the recent jurisprudence of the UNCLOS tribunals, such reliance on external rules is widely accepted.Footnote 111 Meanwhile, it must be noted that military activities may be excluded from the compulsory jurisdiction of the UNCLOS tribunals, as Russian claims partially worked in the Dispute concerning the Detention of Ukrainian Naval Vessels and Servicemen. Footnote 112
5. Conclusion
UNCLOS, as the ‘constitution for the oceans’, is applied during armed conflict alongside the law of naval warfare. Under such circumstances, belligerents shall pay due regard to the rights and duties of neutral coastal States over their EEZs. Due regard in this context differs from that in peacetime, and the nature of the obligation may be informed by principles of the law of naval warfare, including military necessity and humanity. Given the rules outlined in States’ military manuals and academic teachings examined throughout this article, a belligerent party would breach its due regard obligations if it causes damage to the offshore infrastructures or fishing vessels within neutral coastal States’ EEZs when the same military objectives could be achieved without causing such damage and incurring additional burdens on its military activities.Footnote 113
Since its entry into force, UNCLOS has been developed by States Parties and UNCLOS tribunals and appears to have strengthened its role as the constitution for the oceans. One of the factors for this strengthening is the incorporation of external rules, which was also emphasised by the recent ITLOS advisory opinion.Footnote 114 Given the non-centralised structure of international law and the international community, it is inevitable that relevant treaties may be developed without formal arrangements. Therefore, to harmonise such external rules with the existing maritime order, the role of UNCLOS as the constitution for the oceans is essential. This article demonstrates how, in relation to the due regard obligation, UNCLOS may work during armed conflict at sea and accommodate the rules of the law of naval warfare, as developed (and developing) in the form of the Newport Manual and Amendment of the San Remo Manual, but not necessarily closely related to UNCLOS.
Regarding external rules, the impact of environmental laws has recently been strengthened. Paragraph 35 of the San Remo Manual states that due regard should also be paid to the marine environment. Furthermore, Rule 44 of the International Committee of the Red Cross’ Study on Customary International Humanitarian Law also provides due regard for the natural environment in military operations.Footnote 115 Given that fishing and seabed resource development are closely linked to environmental issues, due regard for coastal States’ sovereign rights is also connected to due regard for the marine environment. For example, the destruction of a carbon capture and storage facility in an EEZ can cause significant environmental damage. Such damage is also important for determining the nature of the due regard obligation during an armed conflict. However, this question remains to be addressed in future research.
Acknowledgments
The author would like to acknowledge the helpful comments of the anonymous reviewers, which greatly improved this article. This work was supported by JSPS KAKENHI under Grant [Number 23K25454 and 23H00757].
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