Implications of international armed conflicts for neutral EEZs

An international armed conflict (IAC) is defined by a relatively low threshold as it exists as soon as one or more States resort to armed force against another State, regardless of the conflict’s intensity or duration.Footnote ²² This threshold is deliberately kept low to reflect the dual purposes of the law of armed conflict (LOAC): both to limit the effects of armed conflict and to govern the lawful conduct of military operations.Footnote ²³ The characterization of the conflict by States is irrelevant, as the existence of an IAC is based solely on the prevailing facts demonstrating the de facto existence of hostilities.Footnote ²⁴ For an IAC to exist, there must be an actual resort to military force by a State against another State, but not every confrontation or encounter at sea between State actors is sufficient to trigger an IAC.Footnote ²⁵ Whether an IAC exists as a matter of law is also significant in the current discourse because it determines the legal status of maritime zones of both neutrals and belligerents and, consequently, the body of law that applies in those zones, which can radically alter the legal constraints on foreign naval activities therein.Footnote ²⁶

Under UNCLOS, the ocean is divided into different maritime zones. For the purposes of naval warfare, however, the LONW, which is part of the LOAC, overlays this zonal approach with a functional distinction between two categories of waters.Footnote ²⁷ The first consists of “neutral waters”, a term not found in UNCLOS but used in the LONW to refer to maritime zones under the full sovereignty of neutral States (internal waters, territorial sea and, where applicable, archipelagic waters), in which belligerent military operations are prohibited.Footnote ²⁸ The second category consists of all waters beyond those neutral waters, in which certain “hostile actions” by belligerent forces may be undertaken.Footnote ²⁹ This includes waters under the full sovereignty of the belligerents (“belligerent waters”), the EEZs of both neutral and belligerent States, and the high seas.Footnote ³⁰ These so-called “hostile actions”, also described elsewhere as “belligerent rights”,Footnote ³¹ encompass a range of military activities at sea, including the conduct of hostilities, visit and search, capture, blockades and exclusion zones.Footnote ³² Such belligerent activities may be restricted or unlawful in peacetime but may become permissible once the threshold of IAC has been crossed.

Consequently, the existence of an IAC, and the resulting applicability of the LONW at sea, particularly in a neutral EEZ, determines whether foreign military activities in those waters are assessed as peacetime military uses governed by UNCLOS or as wartime operations governed by the LONW, and thus the applicable legal limits on those activities. This determination affects not only the conduct of military activities by foreign belligerents and the exercise of neutral coastal States’ sovereign rights and jurisdiction, but also the exercise of other neutral States’ high seas freedoms, such as navigation and the laying of submarine cables in the neutral State’s EEZ. As widely noted in the literature, the determination of whether and when an IAC exists is sometimes contested,Footnote ³³ much like the question of which legal regime applies to particular areas.

UNCLOS’s continued applicability during wartime

Because IACs are occurring continuously in different parts of the worldFootnote ³⁴ and the LONW imposes no geographical limit on naval operations beyond the protection of neutral waters, an IAC can, in principle, render vast stretches of the global ocean potential theatres of belligerent activities. In effect, the oceans risk being divided into “neutral waters” and “areas of naval warfare” nearly all the time, which is a result that sits uneasily with UNCLOS’s commitment to “peaceful uses of the seas and oceans”.Footnote ³⁵

Under the LONW, belligerent operations are not confined to belligerent territory but may occur anywhere beyond neutral waters. For distant neutral States, however, armed conflict may have no meaningful presence unless belligerent operations are projected into their maritime zones. Neutrals may reasonably question, for example, why their EEZs, which are otherwise governed by a peacetime legal framework under UNCLOS, should be subjected to a wartime regime merely because belligerents choose to conduct hostilities beyond their own waters.

Therefore, the idea that any IAC could automatically permit belligerent operations anywhere in the world, beginning just 12 nautical miles off any neutral coastline, would potentially be met with resistance by some neutral States. Under the traditional law of maritime neutrality, a neutral State’s inviolable “neutral waters” extend only to its territorial sea, internal waters and archipelagic waters, within which belligerents are prohibited from establishing bases of naval operations against their adversaries.Footnote ³⁶ Beyond this limit, the LONW permits belligerents to exercise their rights, such as attack, capture, minelaying, visit, search or diversion.Footnote ³⁷ Rather than requiring neutrals to adjust their rights and uses of the EEZ to accommodate wartime rules and belligerent needs, this raises the countervailing question of whether belligerents should instead be required to restrain their conduct to peacetime legal limits when operating beyond their own and enemy territory, including when operating within neutral EEZs and the high seas where neutral rights continue to exist. Neutrals may then insist that UNCLOS should continue to govern activities in areas beyond belligerent territory at all times.Footnote ³⁸

The argument that UNCLOS would apply beyond belligerent territory at all times would mean that all naval operations by foreign military assets in neutral EEZs would be governed as “military activities”, which are not defined under UNCLOS but would generally fall under Article 58’s “other internationally lawful uses of the sea”.Footnote ³⁹ This means that belligerent activities which may qualify as lawful “hostile actions” or be characterized as “belligerent rights” under the LONW would instead be assessed under a peacetime legal framework, which is more restrictive than the LONW. Moreover, those activities could then be subject to compulsory dispute settlement under Part XV of UNCLOS, unless the relevant States have made an optional declaration under Article 298(1)(b) to exclude military activities from the compulsory jurisdiction,Footnote ⁴⁰ or one of the parties to the dispute is not a party to UNCLOS.Footnote ⁴¹ One author has argued that the availability of this optional declaration itself suggests that UNCLOS was intended to remain applicable even during armed conflict.Footnote ⁴²

Furthermore, the view that UNCLOS should continue to apply during wartime, including in neutral EEZs, would require belligerents to comply with their peacetime obligations owed not only to the neutral coastal State but also to other neutral user States. Central among these obligations is the due regard obligation under UNCLOS, which seeks to balance the interests of coastal States and other States in the EEZ.Footnote ⁴³ In the Chagos Marine Protected Area [MPA] arbitration, the Arbitral Tribunal found that this obligation requires a balancing act between competing rights based upon an evaluation of the extent of the interference, the availability of alternatives and the importance of the rights and policies at issue.Footnote ⁴⁴ This assessment will often involve at least some prior consultation with the relevant rights-holding State.Footnote ⁴⁵ Consequently, the continued applicability of UNCLOS beyond belligerent waters would require competing rights to be balanced rather than treating any one set of rights as automatically prevailing.

More importantly, as discussed above, a failure to comply with the due regard obligation may expose the relevant State to the compulsory dispute settlement mechanism. In this sense, the continued applicability of UNCLOS offers neutrals not only a substantive protection of their EEZ rights, but also a procedural framework through which alleged infringements may be assessed and challenged. At the same time, however, belligerents invoking the LONW may contend that their conduct remains lawful on the basis that the LONW displaces UNCLOS in the event of any inconsistency.Footnote ⁴⁶ In such circumstances, belligerents may contest the jurisdiction of any court or tribunal acting under Part XV, arguing that disputes arising from belligerent naval operations fall outside UNCLOS’s compulsory dispute settlement regime.

Consequently, where belligerents and neutrals assess a similar conduct through different bodies of law, legality becomes framework-dependent, giving rise to reciprocal allegations of non-compliance. A neutral State may challenge belligerent operations on the basis that the belligerent has failed to meet its due regard obligation in the neutral EEZ; belligerents, by contrast, may contend that such obligation applies only in peacetime and is displaced during armed conflict by the LONW. From this perspective, belligerents may further argue that neutral coastal States exceed their lawful competences by seeking to regulate belligerent operations through a peacetime legal framework. The resulting disagreement over the applicable legal framework risks undermining legal certainty rather than promoting legal order, which is the very function that international law is meant to serve.Footnote ⁴⁷

The LONW as lex specialis

Under the LONW, belligerent naval operations may in principle extend to any waters outside neutral waters. In practice, however, the geographic reach of such operations depends on both a belligerent’s capacity to project force beyond its own and its enemy’s territory and the permissibility of such operations under applicable international law. Where belligerents seek to undertake activities that may qualify as “hostile actions” or “belligerent rights” in neutral EEZs, the LONW affords a broader range of permissibility than UNCLOS. As discussed, this expanded permissibility hinges on the existence of an IAC, which activates the LONW and determines the legality of belligerent activities. Once the threshold of armed conflict has been met, this specialized regime provides the necessary authority for the conduct of hostilities that would otherwise be restricted or impermissible under UNCLOS.

Belligerents, particularly naval powers capable of operating beyond their own waters, would therefore characterize the LONW as the lex specialis, arguing that in the event of a direct normative conflict, it prevails over UNCLOS.Footnote ⁴⁸ Where no such conflict arises, UNCLOS continues to apply. For instance, rules governing matters such as baselines, the breadth of the territorial sea and the delineation of maritime zones are generally understood to remain applicable, as they define neutral territory.Footnote ⁴⁹ What remains contested is which peacetime constraints under UNCLOS survive armed conflict and which are displaced.

In this regard, it is worth noting that much of the LONW was developed in a pre-UNCLOS and largely colonial context,Footnote ⁵⁰ in which maritime space was merely categorized as either territorial seas or high seas.Footnote ⁵¹ UNCLOS fundamentally altered this structure by introducing additional maritime zones, most notably the EEZ, which is neither part of the high seas nor territorial seas, but preserves certain high seas freedoms insofar as they are compatible with the EEZ regime.Footnote ⁵² This development has prompted calls to revise the LONW in order to maintain legal order and stability at sea, but such efforts have thus far proven politically unattainable.Footnote ⁵³

In the absence of any State-led process to codify and update the rules of naval warfare, interpretive guidance has largely been left to expert manuals that seek to assess how customary naval warfare rules apply in light of the new maritime zones and the associated rights and obligations introduced by UNCLOS.Footnote ⁵⁴ The most notable among these is the San Remo Manual, adopted in 1994 by an international group of legal and naval experts that included academics, government lawyers and naval personnel participating in their individual, personal capacities.Footnote ⁵⁵ The more recent Newport Manual, adopted in 2023 and revised in 2025, drew on a more geographically and institutionally limited pool of contributors.Footnote ⁵⁶ These manuals reflect areas of both convergence and divergence on a number of key issues that could affect the limit of belligerent activities in the EEZ.Footnote ⁵⁷

Unlike the San Remo Manual, which contains no explicit provision addressing the conflict of norms,Footnote ⁵⁸ the Newport Manual takes a clear position by invoking the lex specialis derogate legi generali principle to de-conflict the relationship between UNCLOS and the LONW.Footnote ⁵⁹ Procedurally, this broad displacement of UNCLOS means that belligerent conduct would likely fall outside the compulsory dispute settlement mechanisms under Part XV of the Convention, limiting the ability of neutral coastal States to challenge such conduct even where it interferes with their sovereign rights and jurisdiction in their own EEZs.

Against this background, the provisional measures proceedings between Ukraine and Russia before the International Tribunal for the Law of the Sea (ITLOS) are instructive – not for what the Tribunal decided, but for the questions it left unanswered.Footnote ⁶⁰ In this case, Russia denied the characterization of the situation between the two States as an armed conflict for the purposes of international humanitarian law (IHL),Footnote ⁶¹ and the ITLOS did not interrogate that assertion, proceeding instead on the basis that the dispute concerned the interpretation or application of UNCLOS.Footnote ⁶² The Tribunal’s approach is notable, as the existence of an IAC is determined on the basis of objective facts demonstrating the de facto existence of hostilities rather than on the characterization adopted by the parties.Footnote ⁶³

The ITLOS’s approach was, however, met with internal caution. In his Dissenting Opinion, Judge Roman Kolodkin leveraged Ukraine’s own position to classify the incident as an excluded “military activity”. He observed that Ukraine had consistently characterized the incident as an “act of aggression” occurring in the context of an “armed conflict” and had demanded “prisoner of war” status for its detained servicemen for months before shifting to a law enforcement argument.Footnote ⁶⁴ On that basis, he concluded that the events were fundamentally “military activities” in nature.Footnote ⁶⁵ Critically, his objection to jurisdiction rested not on the existence of an armed conflict as such, but on the fact that both States had submitted optional declarations under Article 298(1)(b) of UNCLOS excluding military activities from dispute settlement.Footnote ⁶⁶ By treating belligerent conduct during an armed conflict as “military activities” within the meaning of Article 298(1)(b), Judge Kolodkin’s logic implicitly treats UNCLOS as continuing to apply during armed conflict and considers that its compulsory dispute settlement mechanism applies equally, unless a party has filed a declaration excluding military activities under Article 298. As Judge Liesbeth Lijnzaad rightly cautioned, this case demonstrated a “difference of opinion as to the interpretation and application of the laws of armed conflict, for which this Tribunal has no jurisdiction”.Footnote ⁶⁷ In her declaration, she also expressed reluctance regarding the ITLOS’s succinct treatment of the applicable law.Footnote ⁶⁸

By not engaging with whether an IAC existed between the parties, the ITLOS also avoided the question of whether the LONW displaced UNCLOS for the purposes of Part XV jurisdiction, and whether it would have had jurisdiction had the incident been characterized as involving belligerent activities. Moreover, the ITLOS characterized Russia’s actions as peacetime maritime law enforcement, a characterization that also had the effect of circumventing Russia’s optional declaration excluding disputes concerning military activities from compulsory jurisdiction.Footnote ⁶⁹ This approach suggests an interrelationship between conflict qualification, activity characterization and the availability of jurisdiction under Part XV. It leaves open the possibility that in future cases, tribunals may preserve jurisdiction by refraining from engaging with the threshold question of armed conflict.

If similar disputes arise in the future, a tribunal’s reluctance to determine whether an IAC exists and, consequently, which legal regime governs the conduct in question could prove particularly costly – especially for belligerents – in cases involving belligerent operations in neutral EEZs. As discussed, the LONW permits a considerably wider range of military activities in the EEZ than UNCLOS does in peacetime. Therefore, if such conduct is assessed against peacetime UNCLOS standards, it may be found to violate UNCLOS when it is permissible under the LONW. A tribunal that sidesteps the conflict qualification question therefore does not merely defer a difficult issue; it prejudges the outcome by selecting the more restrictive legal standard by default.

That said, a violation of IHL is not automatically or necessarily a violation of UNCLOS, because the two regimes are structurally distinct,Footnote ⁷⁰ and any conflict between their particular norms must be assessed on a norm-specific basis rather than presumed from the relationship between the regimes as a whole.Footnote ⁷¹ It is possible, however, that the same conduct which violates IHL also independently violates UNCLOS, where that conduct falls within the specific material scope of both regimes simultaneously.Footnote ⁷² For example, an IHL violation involving “widespread, long-term and severe” environmental harmFootnote ⁷³ could simultaneously violate UNCLOS’s marine environmental protection obligationsFootnote ⁷⁴ if the damage extends to the marine environment, because both norms are breached by the same act. Another example is where belligerent conduct causing a merchant vessel to sink and leak pollutants could violate IHL rules on attacks against civilian objects, while the resulting pollution independently violates the obligation to prevent marine pollution from ships under UNCLOS.Footnote ⁷⁵

The existence of the due regard obligation during armed conflict

In the future, it would not be inconceivable to see a case brought before the ITLOS that involves the interpretation or application of the due regard obligation in the EEZ during armed conflict. Where UNCLOS compulsory dispute settlement is activated and belligerent activities in a neutral EEZ are characterized as military activities in the manner suggested by Judge Kolodkin’s reasoning, there is a possibility that a court or tribunal may adopt the same interpretation as in the Chagos MPA arbitration, construing due regard as requiring at least some prior consultation with the relevant rights-holding States.Footnote ⁷⁶ Transposing that peacetime standard into an armed conflict context would prove operationally restrictive for belligerents, though a wartime due regard standard – the content of which remains uncertain – would not necessarily produce a more favourable outcome for them. As noted previously, neither the existence of the due regard obligation during armed conflict nor its content has been definitively resolved, leaving open the questions of both whether it binds belligerents operating in a neutral EEZ and what it actually requires of them.

In this respect, the Newport Manual treats due regard as a peacetime obligation that does not apply during armed conflict, noting that “[n]o State has asserted the right to restrict belligerent naval operations during armed conflict at sea beyond the territorial sea since the Organization of American States adopted the Panama Declaration on October 3, 1939”.Footnote ⁷⁷ Moreover, one author has argued that due regard is deemed incompatible with the operational requirements of naval warfare.Footnote ⁷⁸ The Newport Manual’s position stands in contrast to that of the San Remo Manual, Rule 12 of which asserts that “[i]n carrying out operations in areas where neutral States enjoy sovereign rights, jurisdiction, or other rights under general international law, belligerents shall have due regard for the legitimate rights and duties of those neutral States”.Footnote ⁷⁹

Two features of this provision are worth noting. First, its reference to “neutral States” rather than “neutral coastal States” suggests that the due regard obligation extends beyond the coastal State itself. It may be interpreted to mean that belligerents operating in a neutral EEZ owe an obligation of due regard not only to the neutral coastal State, but also to other neutral States exercising residual high seas freedoms in those waters, including navigation, overflight and the laying of submarine cables and pipelines.Footnote ⁸⁰ Second, the San Remo Manual elaborates on this obligation specifically in the context of hostilities in a neutral EEZ where belligerents shall have “due regard” for the neutral coastal State’s sovereign rights over resources and its jurisdiction over the marine environment, as well as for artificial islands, installations, structures and safety zones established by neutral States.Footnote ⁸¹ Specifically, Rule 34 of the San Remo Manual stipulates that

Under UNCLOS, the due regard obligation applies reciprocally in peacetime, requiring both coastal States and other States to have due regard for each other’s rights and duties in the EEZ.Footnote ⁸³ This reciprocal architecture likely persists during armed conflict. Although the San Remo Manual explicitly imposes the due regard obligation only on belligerents, the neutral coastal State arguably retains a correlative obligation under UNCLOS to have due regard to the belligerent’s rights. In practical terms, just as a belligerent may not unnecessarily destroy offshore installations in a neutral EEZ, the neutral coastal State must in turn pay due regard to the belligerent’s right to conduct military activities, such as attacking enemy warships, within that zone. The content of that reciprocal obligation may not mirror its peacetime scope, but its continued existence matters for both parties.

The San Remo Manual adopts the due regard obligation across several provisions, particularly where belligerent activities intersect with neutral rights, but it does not leave the content of that duty entirely to interpretation. For arguably one of the most disruptive categories of belligerent activity, the San Remo Manual supplements the baseline due regard obligation with more specific, concrete requirements. Rule 35 is the clearest example, providing that

Read together with Rule 34, this would imply that in the context of minelaying, the protection of neutral EEZ rights does not rest solely on an open-ended balancing test. Instead, the due regard duty is given operational content through mandatory procedural requirements – most significantly, the obligation to notify the neutral coastal State before laying mines. This raises the further question of whether equivalent implied requirements attach to the due regard obligation as it applies to other categories of disruptive belligerent activity, or whether the San Remo Manual’s specificity is intentionally limited to minelaying alone.

While the San Remo Manual attempts to harmonize UNCLOS with the LONW, the Newport Manual is consistent with the US view, which maintains 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”.Footnote ⁸⁵ The Newport Manual explicitly characterizes Rules 34 and 35 of the San Remo Manual as lex ferenda: an aspirational attempt or a scholarly expression of progressive development that is not supported by State practice.Footnote ⁸⁶ It further construes due regard as relating primarily to the safety of navigation, rather than to the protection of coastal State sovereign rights and jurisdiction in the EEZ.Footnote ⁸⁷ The Newport Manual finds that

In this sense, the Newport Manual implies prioritization of belligerent rights over both the sovereign rights and jurisdiction of neutral coastal States and other internationally lawful uses of the EEZ by other neutral States during armed conflict. This normative divergence is further reflected in a subtle yet significant terminological difference between the two manuals. The San Remo Manual’s use of “hostile actions” frames belligerent conduct from the perspective of those affected by it, casting it as something done to others and implicitly acknowledging its harmful character. The Newport Manual’s framing of comparable conduct as the enacting of “belligerent rights”, by contrast, adopts the belligerent’s own vantage point, recasting the same activities as an entitlement to be exercised rather than an action to be justified. This article observes that the choice of terminology is not merely stylistic but reflects each manual’s underlying orientation toward the competing interests at stake.

Moreover, while the Newport Manual treats any due regard obligation toward neutral EEZ rights as lex ferenda, it simultaneously imposes a “duty to respect” the rights and duties of neutral States.Footnote ⁸⁹ It is also unclear whether the “duty to respect” adopted in the Newport Manual sets a lower or higher threshold than “due regard”. Given the Newport Manual’s belligerent-leaning interpretation, however, the choice of “respect” over “due regard” may suggest that the former imposes a lower standard and is therefore more protective of belligerent operational interests.

According to Roach, the San Remo Manual’s drafters actually considered both standards before settling on “due regard” over “respect”, rejecting the latter as too onerous given its implication of an absolute and affirmative duty inconsistent with the necessities of naval warfare; in light of this, “due regard” was adopted as the standard that better reflects the balance between neutral rights and belligerent operational needs.Footnote ⁹⁰ This choice was also said to reflect a broader scholarly consensus that “due regard” better captures the spirit of mutual accommodation of interests in a way that “respect” does not.Footnote ⁹¹ Although “respect” is traditionally considered an absolute and affirmative duty in the LOAC, the Newport Manual conditions it on consistency with “military necessity” and operational requirements. This arguably renders “military necessity” a trump card, as the belligerent need only respect neutral rights where doing so does not interfere with its operations. Due regard, by contrast, requires an accommodation of interests, obligating the belligerent to weigh its military objectives against neutral rights, and where the balance tips in the neutral State’s favour, the belligerent may be required to alter its operations accordingly.

Nonetheless, even if both manuals were to agree that the due regard obligation remains during armed conflict, it cannot be assumed to carry the same content as in peacetime since its scope is also shaped by other LOAC principles.Footnote ⁹² As discussed, the San Remo Manual has gone some way toward clarifying what due regard requires in the specific context of minelaying, but the content of that obligation for other categories of hostile action remains uncertain. Whether the Chagos MPA arbitration’s interpretation extends to wartime contexts will likely need to be assessed on a case-by-case basis, as a prior consultation requirement may suffice to discharge the due regard obligation in peacetime, but may not always accord with the operational realities of armed conflict. The standard of due regard will therefore vary with the nature of the operation: a sudden attack on an enemy warship, for instance, depends on secrecy and surprise, making prior consultation practically impossible, while a considerably higher standard of engagement may be expected when a belligerent establishes a maritime exclusion zone across a broad stretch of a neutral EEZ. The fact that the due regard standard must be adapted to wartime contexts does not, however, mean that the underlying obligation ceases to exist. Consistent with the International Law Commission’s (ILC) understanding of lex specialis as clarifying or modifying rather than displacing the general law, the due regard obligation should be adapted to the exigencies of armed conflict rather than treated as being extinguished by them.Footnote ⁹³

The vulnerability of neutral EEZs in contemporary naval warfare

Given the divergence among expert manuals on the existence of the due regard obligation during armed conflict, the choice of manual governing such operations is not merely academic – it establishes whether neutral States retain any meaningful protection beyond what a belligerent’s own assessment of its operational needs dictates. Since most modern naval operations during armed conflict are expected to occur within the 200-nautical-mile EEZ,Footnote ⁹⁴ and given the absence of a geographical limit of naval warfare beyond neutral waters and the presence of IACs in different parts of the world, belligerents may in principle conduct operations in any neutral EEZs wherever the law and their operational capacity permit, even today. This reality leaves neutral States exposed, yet many remain legally and strategically unprepared for the extension of hostilities into their 200-nautical-mile zones. Contemporary regional security debates, particularly those concerned with protecting neutral interests from armed conflicts, remain largely focused on the protection of neutral territory, discounting the vast expanse of the EEZ.Footnote ⁹⁵ Yet the economic stakes for neutral States in these zones are considerable, as the following paragraphs illustrate.

First, given that over 90% of all commercially exploitable fish stocks are caught within 200 nautical miles of the coast, hostilities in the EEZ directly threaten both coastal States’ ability to exploit these resources and the livelihoods that depend on them.Footnote ⁹⁶ There are historical instances where submerged submarines have caught the nets of fishing boats and dragged the boats under, often resulting in loss of life.Footnote ⁹⁷ Moreover, the establishment of belligerent exclusion zones may occur during peak fishing seasons and displace fishers from their most productive grounds.Footnote ⁹⁸ The use of live-fire ammunition, explosives and high-intensity sonar during military activities has been protested by fishers for destroying marine habitats, disrupting fish migratory paths and depleting the fish stocks on which local communities depend for their livelihoods.Footnote ⁹⁹

Second, all States enjoy high seas freedoms of navigation in the EEZ, for both military and commercial purposes.Footnote ¹⁰⁰ Under the LONW, belligerents may establish so-called “maritime operational zones” in neutral EEZs, which can be used as a screening mechanism to simplify target identification.Footnote ¹⁰¹ Vessels entering these zones may be required to obtain prior approval or provide identification, and may face diversion or capture if they fail to comply.Footnote ¹⁰² The use of “grey zone” tactics further complicates target discrimination, increasing the likelihood of damage to neutral shipping.Footnote ¹⁰³ Moreover, given that most modern trade is carried by neutral-flagged vessels,Footnote ¹⁰⁴ the conduct of economic warfare in neutral EEZs that overlap with critical sea lanes carries the potential to disrupt global maritime commerce in ways that extend well beyond the neutral coastal States.Footnote ¹⁰⁵ As seen during the Russia–Ukraine IAC, the closure or obstruction of commercial navigation can trigger global food crises.Footnote ¹⁰⁶

Third, beyond the coastal State’s resource interests and all States’ navigation interests, the EEZ is of vital importance to the wider international community as it is home to millions of kilometres of fibre-optic data cables which serve as the foundation for 99% of global communications.Footnote ¹⁰⁷ These cables are inherently transnational connectors often owned by multi-State consortia, meaning that a single line passing through a coastal State’s EEZ typically carries critical data for multiple other States simultaneously.Footnote ¹⁰⁸ Certain EEZs function as “relay stations” where a few cables facilitate the connectivity of nearly fifty different countries across multiple continents.Footnote ¹⁰⁹ Because of this globally interconnected nature, any severance, whether intentional or accidental, does not merely affect the State where the cable makes landfall (the “landing State”), but can simultaneously cut off other States that rely on that cable for internet connectivity, crippling their economies, education systems and government services.Footnote ¹¹⁰ For small island States such as Tonga or Kiribati, which are often served by only one cable, a single act of cable-cutting can result in catastrophic consequences.Footnote ¹¹¹

Fourth, for many States, the marine environment is inseparable from human health and economic security. Military activities before, during and after armed conflict are reported to generate toxic legacies that harm human health and disrupt ecosystems and livelihoods;Footnote ¹¹² attacks on tankers or offshore installations can release millions of barrels of oil, thus despoiling neutral coastlines and resources.Footnote ¹¹³ Furthermore, the environmental consequences of naval warfare are not always immediate: ships sunk during combat continue to pose environmental risks as fuel and hazardous materials leak from their hulls over time,Footnote ¹¹⁴ the loss of nuclear-powered or nuclear-armed ships carries risks of radioactive contamination,Footnote ¹¹⁵ and naval mines often remain active long after hostilities cease.Footnote ¹¹⁶ Beyond these conventional threats, the destruction of emerging maritime infrastructure such as carbon capture and storage facilities or offshore wind farms in the EEZ carries severe contamination and economic risks for neutral populations.Footnote ¹¹⁷

Finally, the duty to assist those in distress at sea imposes heavy logistical and financial burdens on neutral States when hostilities occur within their EEZs.Footnote ¹¹⁸ Neutral States receiving survivors must then manage those individuals’ medical care, internment and humanitarian needs, often without adequate resources or compensation.Footnote ¹¹⁹ These cascading effects confirm that an attack in a neutral EEZ is never just an attack on an enemy warship. When hostilities spill into neutral maritime zones, belligerents also shift the human and economic costs of war onto neutral populations.

It is against these various neutral interests that the practical consequences of the doctrinal split between the San Remo Manual and the Newport Manual become starkly apparent. If the San Remo Manual were applied, the obligation to exercise “due regard” would apply generally to all belligerent operations conducted in a neutral EEZ, protecting the legitimate rights of both the coastal State and other third-party neutrals.Footnote ¹²⁰ This baseline duty is complemented by more specific protections for minelaying activities, requiring the belligerent to notify the coastal State of the minefield’s location, to ensure that mines do not endanger artificial islands, installations and structures, and to avoid, so far as practicable, interfering with exploration or exploitation of the zone.Footnote ¹²¹ Since all States enjoy the high seas freedom to lay submarine cables in the EEZ, the due regard obligation must also be read alongside the San Remo Manual’s provision on undersea infrastructure, which requires belligerent forces to take care to avoid damaging subsea cables not exclusively serving the belligerents.Footnote ¹²² As such, both the neutral coastal State and other third-party neutrals would retain a clear normative baseline to invoke these protections.

Conversely, applying the Newport Manual produces a markedly different outcome. The Newport Manual explicitly rejects the San Remo Manual’s “due regard” and mine notification requirements as peacetime rules displaced by the lex specialis of naval warfare,Footnote ¹²³ going considerably further than most national military manuals, which have stopped short of adopting San Remo Rule 35’s strict notification obligations but have not rejected the underlying due regard obligation.Footnote ¹²⁴ While the Newport Manual recognizes a general duty to “respect” neutral rights in the EEZ, that duty is expressly conditioned on consistency with military necessity and operational requirements. If a belligerent determines that military necessity demands the establishment of maritime exclusion zones in a neutral EEZ during peak fishing seasons, the exercise of visit and search along neutral EEZ shipping routes, or minelaying in a neutral EEZ, it would arguably justify bypassing neutral rights entirely. Stripping away both layers of protection leaves neutral States with no objective standard against which a belligerent’s conduct can be measured, and consequently, a belligerent mining a neutral EEZ would bear no obligation to notify the coastal State, leaving neutral fishing fleets, offshore installations and structures, and transiting merchant vessels exposed to unmarked minefields without warning.

The Newport Manual’s treatment of environmental and infrastructure protection follows the same permissive logic. On environmental harm, the Newport Manual abandons the San Remo Manual’s “due regard” standard in favour of a prohibition limited to weapons causing damage that is simultaneously “long-term, widespread, and severe”,Footnote ¹²⁵ measuring “long-term” in decades.Footnote ¹²⁶ Since conventional naval mines, torpedoes and munitions are unlikely to produce environmental degradation on that timescale, the threshold offers neutral coastal States little practical protection against localized but significant damage to the marine environment. On subsea cables, the Newport Manual permits their destruction within a neutral EEZ wherever “the necessities of war require” and the cable makes “an effective contribution” to the enemy’s military effort, regardless of concurrent civilian or neutral use.Footnote ¹²⁷ Although such destruction must comply with core LOAC principles, the Newport Manual simultaneously excludes any resulting “economic or commercial losses” from the definition of collateral damage.Footnote ¹²⁸ In practice, this interpretation means that where a neutral State’s cables carry enemy communications traffic, the belligerent’s proportionality calculus need not account for the disruption to the neutral State’s own internet connectivity, financial systems or commercial operations. The threshold for lawful destruction is thereby made considerably easier to satisfy, at the expense of the neutral State.

The catalyst for lex ferenda

The Newport Manual’s primary objection to the San Remo Manual’s due regard provisions rests on the assertion that San Remo Rules 34 and 35 constitute lex ferenda that does not reflect customary rules of naval warfare. One author has also argued that highly specific operational constraints in Rule 35, including the mandatory mine notification requirement, have attracted fragmented State acceptance and may not yet satisfy the threshold of uniform practice required to constitute lex lata.Footnote ¹²⁹ However, the Newport Manual’s wholesale dismissal overstates that limitation and understates the San Remo Manual’s broader normative influence. In the three decades since its adoption in 1994, the San Remo Manual has been widely relied upon and used as a reference in national legislation and military manuals,Footnote ¹³⁰ with the Danish military manual going so far as to describe the San Remo Manual as “widely considered to reflect customary international law”.Footnote ¹³¹ This process of maturation was aided by the fact that many of the San Remo Manual’s drafters were senior civil servants or retired military officers who served as informal conduits to their respective national authorities and encouraged domestic adoption.Footnote ¹³² The fact that some States have incorporated the core due regard obligation into their operational doctrines, even while omitting or modifying the San Remo Manual’s stricter procedural requirements on minelaying, demonstrates that the core obligation has achieved considerable traction in State practice, notwithstanding ongoing contestation over its precise content.Footnote ¹³³

Even if the Newport Manual is correct in observing that the San Remo Manual reflects some elements of progressive development of law (lex ferenda),Footnote ¹³⁴ this article treats such lex ferenda elements not as a deficiency, but as a necessary avenue through which the LONW can better accommodate neutral interests that have historically been under-represented in the LONW.Footnote ¹³⁵ The LONW was developed in a predominantly colonial context where power asymmetry was not only evident but also accepted as the norm. This is reflected in the narratives of “civilized nations” used during the negotiation of early naval warfare treaties, which systematically excluded the voices of so-called “uncivilized” States – i.e., those entities that were deemed not to meet the nineteenth-century European “standard of civilization” – from international lawmaking.Footnote ¹³⁶ By contrast, the EEZ regime was advanced through the UNCLOS negotiations as a more geopolitically inclusive process, involving newly independent and formerly colonized States that had previously been excluded from the elitist “civilized nations” grouping.Footnote ¹³⁷

Accordingly, the contestation over how wartime rules apply in the EEZ reflects these longer-standing structural tensions between a postcolonial reallocation of maritime rights and the desire of established naval powers to preserve their operational freedoms at sea. By confining some of the San Remo Manual’s neutral-protective norms to lex ferenda, the Newport Manual may inadvertently undermine the San Remo Manual’s authority while reinforcing its own position as the more authoritative reading of the applicable LONW.Footnote ¹³⁸ The lex ferenda label therefore risks silencing the legal conscience of postcolonial States, reproducing earlier patterns of exclusion and limiting their ability to influence the very norms that directly affect their sovereign rights and interests.Footnote ¹³⁹

Seen in this light, the emergence of lex ferenda elements in contemporary interpretations of naval warfare law is not surprising. Where legal regimes are recalibrated through the inclusion of interests and perspectives previously excluded from norm-making, pressures for normative development are inevitable. The question, therefore, is not whether such lex ferenda arguments arise, but to what extent they should be accommodated or constrained within an existing legal framework that continues to govern armed conflict at sea.Footnote ¹⁴⁰ These questions become more pressing in light of the changing uses of the sea, especially in the EEZ and high seas.

The LONW was developed in a world very different from that of today. Even by 1982,Footnote ¹⁴¹ when UNCLOS was adopted, technological developments had already begun to reshape the uses of the sea.Footnote ¹⁴² As discussed previously, the EEZ hosts a wide range of critical activities and infrastructure, including fishing and commercial shipping, as well as submarine cables and offshore renewable energy infrastructures.Footnote ¹⁴³ This increasingly complex landscape means that far more interests are at stake in the EEZ than those of the coastal State alone, as other States also rely on the zone for a variety of economic activities – for example, flag States of vessels transiting the EEZ for commercial navigation and States whose economic interests depend on submarine telecommunications and power cables passing through the zone.Footnote ¹⁴⁴ Yet the relationship between norms under UNCLOS and the LONW during armed conflict remains unsettled, creating a potential source of tension between belligerents and neutrals.

That relationship is one not of mutual exclusion but of co-applicability, with lex specialis serving to resolve specific norm conflictsFootnote ¹⁴⁵ – yet invoking lex specialis also presupposes a settled body of naval warfare law to displace UNCLOS, which is a questionable assumption. Most of the LONW derives from customary international law rather than modern treaties,Footnote ¹⁴⁶ and that reliance on custom is itself problematic because the traditional customary rules were forged almost exclusively through the practice of a handful of imperial powers, and this largely unmodified regime has never been comprehensively updated to account for the contemporary community of States or the modern law of the sea. In this vacuum, expert manuals have assumed an outsized role in articulating how the two regimes interact, making the choice of which manual represents the authoritative reading of that interaction a question of considerable consequence – as evidenced by the debate over whether due regard exists during armed conflict.

Lex lata: Whose State practice counts?

That said, belligerent conduct in neutral EEZs has the potential to test the differing legal positions adopted by neutral States vis-à-vis belligerent operations in their EEZs. These dynamics raise broader questions concerning the formation and interaction of customary international law. Building on the structural asymmetries identified earlier, it is necessary to further elaborate on two interrelated questions: which existing naval warfare rules have actually crystallized into custom, and whose practice and opinion counts in making that determination? A third, more difficult question involves asking how the customary LONW should be interpreted in light of the customary law of the sea; this interaction goes beyond a technical adjustment of rules, as it represents a struggle over who has the power to define the law and the processes used to create it.Footnote ¹⁴⁷ Reconciling these bodies of law shaped by markedly different constellations of actors, interests and objectives requires recognizing that the LONW was largely developed within a historically exclusive circle of colonial naval powers, while the modern law of the sea was negotiated through a more inclusive process in which newly independent and formerly colonized States sought to recalibrate the distribution of rights and powers at sea.

By claiming to reflect a strict restatement of existing law (lex lata) based on State practice and opinio juris,Footnote ¹⁴⁸ the Newport Manual may attempt to shape custom while coding State silence as tacit acceptance. If the position adopted by the Newport Manual – that no due regard obligation exists with respect to EEZ rights and jurisdiction during armed conflict – crystallizes into custom, it binds all States regardless of treaty ratification. If the opposing position crystallizes instead, Newport Manual-aligned States may invoke “persistent objector” status as an escape route to avoid being bound.Footnote ¹⁴⁹ In either scenario, the outcome favours those with the power to shape custom in the first place. That power, however, has never been evenly distributed, resulting in a “deep democratic deficit” in the formation of custom,Footnote ¹⁵⁰ and the LONW arguably stands as a prime illustration of this.

The identification of lex lata is also complicated by the variability of State practice itself. In the context of the due regard obligation, for instance, national military manuals reveal uneven terminology and differing degrees of commitment to due regard obligations in the EEZ, making it difficult to characterize the law as settled or uniform. While several national manuals acknowledge the need to take account of coastal State interests in the EEZ, they often do so using less precise language than the San Remo Manual and without consistently adopting its full set of obligations.Footnote ¹⁵¹ In particular, some manuals replace the terminology of “due regard” with more general formulations such as “taking into account”, suggesting a differently conceived standard than that articulated in the San Remo Manual.Footnote ¹⁵² Moreover, only a limited number of military manuals incorporate the San Remo Manual’s detailed obligations concerning naval mining in the EEZ;Footnote ¹⁵³ others refer more broadly to respect for legitimate uses by other States, without specifically addressing the position of neutral coastal States or the protection of offshore structures.Footnote ¹⁵⁴

It is also worth noting that many States, including in Asia, Africa and Latin America, have not publicly articulated their positions on the LONW, let alone produced publicly available military manuals.Footnote ¹⁵⁵ Where such manuals do exist in the public domain, they are likely not available in English, further limiting their visibility and accessibility. As a result, the picture of State practice derived from national military manuals is necessarily partial and potentially skewed.

Therefore, by focusing on lex lata, the Newport Manual’s methodology also relies on a historical record in which the great body of custom was shaped by a handful of States. This instance may reflect a broader tendency to prematurely conclude that one’s policy preferences, particularly when shared by a group of Western States and their allies, represent lex lata based on State practice and opinio juris, which by extension implies a rule of customary law.Footnote ¹⁵⁶ While the lex lata approach may appear neutral, it actually conceals these power imbalances and the imperial origins of the law, privileging the practice of a few powerful navies whose conduct is not only the most visible and systematically documented, but is also that of those States which possessed the resources to participate in naval conflicts and articulate their legal positions on various issues long before decolonization. This results in the legal views and interests of mostly neutral postcolonial and non-naval powers being marginalized, thereby producing a body of law that is more favourable to belligerents. The practice of these States is rarely compiled, published, or translated into English, not only due to significant human and financial resource constraints but also because these States were forced to “implicitly consent” to rules established during a period of high imperialism, when they were not party to the conflicts from which the relevant custom is said to have emerged.Footnote ¹⁵⁷

As discussed previously, the question of what constitutes lex lata and what constitutes lex ferenda may overlook the fact that the San Remo Manual has been adopted domestically by many States, including naval powers such as the United Kingdom and Germany, which have also incorporated San Remo Manual provisions on due regard into their national military manuals.Footnote ¹⁵⁸ The Newport Manual characterizes such inclusion as reflecting a “peacetime standard of due regard, which is not applicable during times of armed conflict”.Footnote ¹⁵⁹ This characterization may be explained by the Newport Manual’s reliance on the US position that operational conduct on the ground carries greater evidentiary weight than military manuals or other official statements in the assessment of State practice.Footnote ¹⁶⁰ In doing so, the Newport Manual implicitly establishes a predetermined hierarchy among the various forms of State practice. This raises the question of how to treat State practice in cases where what a State says and what it does diverge, and whether such divergence itself signals the absence of consistent State practice.

The role of lex ferenda in rebalancing the LONW

Building on these observations, this article finds that the San Remo Manual offers a middle-ground position, as it acknowledges the permissibility of belligerent operations in the EEZ while simultaneously limiting those operations through the requirement of due regard for the coastal State’s economic and environmental rights as well as the legitimate rights of other neutral States.Footnote ¹⁶¹ By maintaining due regard as a continuing legal constraint in the EEZ even during armed conflict,Footnote ¹⁶² the San Remo Manual mirrors the broader decolonization process that has gradually permeated various branches of international law, and which this article argues should equally shape the development of the LONW.

One author has argued that importing UNCLOS due regard obligations into the LONW would “impose additional burdens on belligerents” and “diminish rights of belligerents”,Footnote ¹⁶³ thereby “undermining deterrence” by “eroding the operational flexibility” of naval forces.Footnote ¹⁶⁴ However, the very logic invoked to resist due regard obligations – that they impose additional burdens and diminish rights – applies with equal if not greater force to neutral States. The absence of such obligations effectively requires postcolonial neutral States – many of which are still recovering from the economic devastation of the colonial era – to absorb the environmental and economic costs of armed conflict in order to preserve the operational freedom of belligerent powers.Footnote ¹⁶⁵

The inclusion of the due regard obligation, which has been described as one of “the great organising principles of the law of the sea”,Footnote ¹⁶⁶ illustrates how the San Remo Manual incorporates into the historically imperialist LONW one of the “grand bargains” struck under UNCLOS between “developed States”, which are predominantly former imperial powers, and “developing States”, many of which have emerged from colonial status.Footnote ¹⁶⁷ As noted previously, the transposition of the Chagos MPA arbitration’s interpretation of the peacetime due regard standard to a wartime context is not without difficulty, given the operational realities of armed conflict. While the content of the wartime due regard obligation is still unclear,Footnote ¹⁶⁸ accepting the San Remo Manual as the authoritative restatement of the modern LONWFootnote ¹⁶⁹ would at least mean accepting that belligerents must avoid a purely unilateral and self-serving assessment of their rights and interests and must make efforts to accommodate competing rights and interests while fulfilling their military objectives. Even under the more restrictive peacetime framework, due regard should be interpreted not as a consent requirement from either side but as a balancing exercise that reflects the shared-use nature of the EEZ. A fortiori, the same should apply during armed conflict, where, although the applicable framework is generally more permissive of belligerent activities, the LOAC itself embodies a balancing exercise between the principles of military necessity and humanity.Footnote ¹⁷⁰

Drawing these threads together, UNCLOS functions as a postcolonial equalizer of rights and interests at sea, having been concluded through a broadly representative and multilateral negotiation process involving the majority of States. Unlike the LONW, which was developed largely by a small circle of colonial powers and reflected the dichotomy between so-called “civilized” and “uncivilized” States, UNCLOS embodies a more inclusive legal order grounded in the principle of equality among States.Footnote ¹⁷¹ As such, the San Remo Manual’s incorporation of lex ferenda elements at the time of its drafting can be understood as an extension of the rebalancing that UNCLOS itself represents. Erasing the San Remo Manual’s due regard obligations, particularly where neutral interests are implicated, risks reviving elements of an earlier era marked by blatant power asymmetries, in which States possessing power-projection capabilities were able to subordinate the rights and interests of weaker actors. This is not to deny the persistence of such asymmetries in the contemporary, postcolonial international system, especially at a time when some major powers appear increasingly willing to sideline multilateralism and international law. These considerations caution against uncritically treating the State practice, or policy preferences, of naval powers as determinative of lex lata, and suggest that peacetime obligations under UNCLOS, such as the due regard obligation, cannot be automatically discarded simply because dominant naval powers have historically resisted their application during armed conflict.

The argument advanced in this article goes further than a defence of the San Remo Manual’s harmonization approach. The due regard debate is not merely a technical disagreement about norm conflict resolution, but a site where deeper structural biases in the making of the LONW are most visible. Where newer, broadly negotiated instruments such as UNCLOS reflect a more balanced accommodation of the competing rights and interests of all States, this article argues that they carry significant interpretive weight when reading century-old naval warfare rules against the contemporary law of the sea. Ultimately, the San Remo Manual’s incorporation of key UNCLOS provisions, such as due regard, is not a mere aspirational development, but a necessary legal corrective to ensure that specialized rules of naval conflict are not used as a strategic tool to restore imperial-era power asymmetries at the expense of States whose interests were historically marginalized in the development of the LONW.

State silence in the development of the LONW

The critique that certain progressive norms on naval warfare lack sufficient grounding in State practice is not without merit – after all, existing manuals are drafted by self-appointed experts and may not capture the full spectrum of State positions, even when they claim to reflect only lex lata. Yet, even where such manuals purport merely to restate existing law, one question remains regarding what interpretive weight should be accorded to the silence of others. This is not merely a methodological question but also one about whose experience of war and whose interests in peace have been allowed to shape the content of the law.

Beyond manuals, several IACs since the adoption of UNCLOS in 1982 could, in principle, provide relevant State practice for assessing how both belligerents and neutral coastal States understand the existence and scope of any due regard obligation applicable to belligerent operations in neutral EEZs. During the US-led military operations accompanying the 2001 invasion of Afghanistan (Operation Enduring Freedom),Footnote ¹⁷² for example, the US and its allies conducted boarding and capture operations on thousands of vessels in the Arabian Sea and the Gulf of Oman, which encompass the EEZs of twelve neutral States.Footnote ¹⁷³ It has been argued that there was no evidence that such operations were constrained by the resource rights of the coastal States concerned.Footnote ¹⁷⁴ Similarly, during the Russia–Ukraine conflict, neutral coastal States whose EEZs were affected by belligerent naval operations, such as Romania, Bulgaria and Turkey, did not formally protest on the basis of an alleged failure to exercise due regard for their EEZ rights.Footnote ¹⁷⁵

At first glance, this absence of protest might be read as tacit acceptance that no obligation to exercise due regard exists during armed conflict; however, the evidentiary value of this practice warrants caution. It is uncertain to what extent State practice observed in particular regions can be treated as representative of the positions of neutral States more broadly, as the identification of custom often relies on the “specially affected States” doctrine,Footnote ¹⁷⁶ which grants disproportionate weight to the actions and omissions of States whose interests are most directly impacted by a particular activity.Footnote ¹⁷⁷ If this logic is followed, the only relevant State practice in respect of the due regard obligation in the Black Sea would be that of the regional neutral coastal States which are directly affected by naval hostilities, whereas the opinions of distant Pacific States, for instance, may be viewed as having little relevance because these States lack the direct geographic or strategic nexus to the conflict that would necessitate a legal reaction.Footnote ¹⁷⁸

However, relying solely on the practice of those in the immediate theatre of war effectively allows a handful of States to shape global standards while the attitudes of the broader community are left unaccounted for.Footnote ¹⁷⁹ As noted in the introduction to this article, TWAIL draws attention to a structural imbalance in how customary international law is identified. The operational practice of powerful, well-resourced States tends to crowd out the legal conscience of the wider international community,Footnote ¹⁸⁰ including States that have been historically marginalized from international lawmaking and have little or no naval experience. This is not a challenge to the two-element framework for identifying custom; rather, it is a call to scrutinize whose practice and opinio juris count in that process and to give greater weight to the views of the broader international community as a check on the outsized influence of dominant naval powers.

Furthermore, the absence of protest by distant neutral States should not presumptively be equated with acquiescence because for silence to constitute acquiescence, a State must have actual or constructive knowledge of a claim that is “notorious” enough to demand a response.Footnote ¹⁸¹ In many instances, political, strategic or security considerations, such as the desire to maintain neutrality or exercise restraint in order to avoid diplomatic escalation, may constrain States from articulating legal claims.Footnote ¹⁸² Consequently, silence may reflect a calculated policy of restraint or political pragmatism rather than an opinio juris that accepts, for instance, the absence of a due regard obligation for neutral EEZ rights in wartime.

As noted earlier, the absence of a State-led process to update the LONW has created space for expert-driven initiatives, often organized through invitation-only or self-appointed groups. While these initiatives respond to a genuine regulatory gap, they also risk reproducing patterns of exclusivity that have historically characterized the development of the LONW. The limited engagement of many States, particularly those that were excluded from earlier lawmaking processes due to colonial subjugation, may reflect not indifference, but a combination of capacity constraints and the perception that their rights and interests have not yet been directly affected by naval warfare rules. Non-binding expert manuals, such as the San Remo Manual and the Newport Manual, may nonetheless exert indirect influence on international law through treaty interpretation or the gradual consolidation of customary norms.Footnote ¹⁸³ At the same time, the absence of any legal obligation to respond to such non-binding instrumentsFootnote ¹⁸⁴ may weaken the inference that silence reflects acceptance of a particular legal position, especially where those instruments themselves diverge on key issues, including the treatment of due regard during armed conflict.

The limits of drawing legal consequences from State silence are further illustrated by analogy to the prohibition of the use of force, which is an obligation erga omnes under customary international law and erga omnes partes under the UN Charter.Footnote ¹⁸⁵ Although the victim State is ordinarily expected to respond to a contested invocation of self-defence, it is far less clear that all other States to whom the obligation is owed are required to react in order to avoid being taken as acquiescing in a controversial legal claim.Footnote ¹⁸⁶ This difficulty is even more pronounced in the context of belligerent operations conducted in neutral EEZs, where the use of force is not directed against neutral States as such, but may nonetheless affect their rights and interests. The hybrid legal character of the EEZ pairs the coastal State’s sovereign rights over resources with certain high seas freedoms enjoyed by all States, such as navigation and cable-laying. This creates a jurisdictional overlap that complicates the identification of the victim State, as an attack may simultaneously impair the coastal State’s resource rights and the high seas freedoms of third States reliant on the EEZ.

Moreover, even where a belligerent uses force and invokes self-defence under Article 51 of the UN Charter, thereby engaging the prohibition of the use of force, which is a jus cogens norm and erga omnes obligation that is owed to the international community as a whole, many States will nonetheless remain silent despite being expected to respond to the alleged violation of that prohibition, and that silence cannot automatically be read as acquiescence to the acting State’s legal claims.Footnote ¹⁸⁷ Similar reasoning applies a fortiori to the due regard obligation. Unlike jus cogens or erga omnes norms, the duty of due regard in the EEZ is not owed to the international community as a whole, but specifically to the relevant coastal State and other neutrals exercising their residual high seas freedoms therein. The silence of third-party distant neutrals in response to a belligerent’s conduct in another neutral State’s EEZ is therefore not indicative of those States’ position on whether the due regard obligation subsists during armed conflict, as their own rights may not be directly affected and their reaction is not legally called for. Thus, the failure of a neutral State to react may also reflect non-participation in the conflict, a lack of institutional or financial capacity to formulate a formal response, or a judgement by the neutral State that its rights are not sufficiently affected to warrant such a response.Footnote ¹⁸⁸ As such, the interpretation of State silence as acquiescence cannot turn on assumptions about a State’s genuine belief, but must depend on whether the surrounding circumstances, such as the notoriety of the claim, reasonably permit silence to be understood as acceptance of a legal claim.Footnote ¹⁸⁹ In contexts marked by legal uncertainty, power asymmetry and uneven participation in lawmaking, silence should therefore be treated with particular caution as evidence of consent.

More fundamentally, the absence of protest by neutral States in specific conflicts does not preclude the possibility that other neutral States, particularly those that have historically objected to foreign military activities in their EEZs in peacetime, may adopt different positions if confronted with comparable situations in the future. As discussed in the introduction to this article, several Southeast Asian States have made such objections and declarations in peacetime contexts.Footnote ¹⁹⁰ To date, however, such States have not been confronted with major armed conflicts requiring them to articulate their positions, including with regards to belligerent operations in neutral EEZs, leaving their wartime views untested.Footnote ¹⁹¹

At the same time, the absence of protest by certain neutral States in recent conflicts may reflect political and strategic considerations rather than a settled legal position. This dynamic is also evident in the case of States whose defence and security relationships may constrain the articulation of legal claims.Footnote ¹⁹² Taken together, these factors highlight the difficulty of treating limited regional practice, or silence in specific conflicts, as conclusive evidence that the law has settled against the existence of a due regard obligation in neutral EEZs during armed conflict. Reliance on such practice risks overstating the degree of normative consolidation and under-estimates the potential for future contestation, especially in regions such as Southeast Asia, where objections to foreign military activities in the EEZ have long been expressed in peacetime but whose wartime positions remain untested.