Introduction
The use of non-warships and non-coast guard cutters for contest operations is a clear feature of current tensions at sea. The use of merchant vessels to cut cables in the Baltic Sea, along with harassment and presence operations by fishing vessels as part of the PRC maritime militia in the South China Sea and in the area around the Senkakus, are but two current examples of this practice. In situations short of armed conflict, this practice raises sometimes challenging questions around the sovereign immunity and state agency of these vessels (which I have written about on EJIL Talk! previously). Should any tensions escalate to armed conflict at sea, however, an additional legal factor must also be considered – the use of auxiliaries.
There are at least three reasons why this is important. The first – which I shall not deal with further in this post – is that during any situation of large scale combat operations at or by sea, the use of auxiliaries to support maritime operations will quickly escalate as expensive, crew-intensive, and relatively scare warships are employed almost exclusively in fighting roles. Refuelling, logistics support, amphibious landing operations, and also (if some current state practice is any indication) mine counter-measure operations (MCM), will tend towards becoming – predominantly or in part – auxiliary roles. This is why significant naval fleets already tend to be supported by significant standing auxiliary fleets – the US, UK, Russia, and the PRC are but some examples of this operational and strategic imperative.
The second reason is that auxiliaries are a sui generis legal category that only really matters if and when an IAC with maritime dimensions is occurring. In the law of naval warfare (LoNW), auxiliaries occupy a middle ground between warships and merchant vessels, which entails a distinct set of rights and liabilities that are differentiated from both of these flanking categories of vessel. This is different from the situation outside of armed conflict, where the law of sea essentially recognises only two categories of ships, and attendant rights and liabilities – sovereign immune vessels (being warships and state vessels on non-commercial service, which the law of sea treats as essentially the same for these purposes – Articles 32 and 95-96), and merchant vessels. The first part of this post will seek to outline the three category LoNW differentiation.
The third reason is that there are a range of legal uncertainties that might, and in the near term likely will, attend the application of law to auxiliary use during armed conflict. In the second part of this post, I will attempt to describe two issues that may require further clarification if and when the law relating to auxiliaries becomes a contested issue: (1) The relative (and therefore susceptible?) modernity of our current definition of ‘auxiliary’, with its attendant challenge of differentiating belligerent rights from auxiliary operational rights; and (2) the challenge of characterising the status upon capture of those controlling an uncrewed auxiliary.
Essential LoNW distinctions
In LoNW, the distinction between an auxiliary vessel and a merchant vessel manifests in at least three main consequences. The first is liability to targeting in that auxiliaries are targetable ab initio in the same way as warships. By contrast, merchant vessels only become liable to attack through conduct. For example, a merchant vessel that is found to be carrying contraband is subject to capture, not attack; however, if that merchant vessels actively seeks to evade capture or the exercise of warship belligerent rights, then it may render itself liable to attack (see the San Remo Manual, rules 41, 59-61 for enemy merchant vessels, and rules 67-69 for neutral merchant vessels; also the Newport Manual, §8.6.3, §8.6.5).
The second point of distinction relates to condemnation after capture. Ownership of a captured enemy auxiliary can convert to the capturing belligerent by virtue of capture: ‘Unlike condemnation in prize, transfers of ownership over military objectives do not require adjudication in a prize court’ (Newport Manual, §9.2). By contrast, ownership of a captured delinquent enemy or neutral merchant vessel only properly converts to the capturing belligerent after condemnation by an appropriately constituted prize court. Incidentally, this is itself an impending challenge, as some major and many middle naval powers do not have adequate prize jurisdiction built into their legislation and adjudicative arrangements. At the moment, it is only really Israel that has had an active prize jurisdiction, although it would certainly be open for Russia and Ukraine to have operating prize courts given the maritime dimensions of their current IAC. However, there are also arguments against (pp1252-1253) the continuation of traditional prize jurisdiction, and this is a further LoNW challenge in and of itself (but is not dealt with in this post).
The third point of differentiation is use of force rights. A merchant vessel is entitled to resist the exercise of belligerent rights – up to and including, for example, ramming a warship attempting to visit or capture that merchant vessel, as occurred in the infamous SS Brussels / Captain Fryatt case in WWI (see here, and here at pp297-299). However, these self-defence / resistance rights as vested in merchant vessels under LoNW do not include the more robust operational rights vested in auxiliaries – rights such as refuelling warships, carrying ammunition, engaging in sea to shore lodgement operations, and so on (on which, more below).
The second differentiation that must be made for LoNW purposes is between auxiliary vessels and warships. Both categories of vessel are sovereign immune, and both are targetable ab initio under LoNW (Newport Manual §8.6.1). However, auxiliaries possess a lesser suite of operational rights than warships in that auxiliaries are not permitted to engage in attacks (noting, however, that in LoNW the scope of ‘attack’ is in some aspects quite maritime specific). For example, an auxiliary can engage in amphibious lodgement – putting military forces ashore (as UK RFA vessels did during the Falklands War in 1982) – but it should not be used as the command and control vessel for an amphibious operation. Likewise, an auxiliary may operate as a mothership for MCM operations, but it cannot be involved in laying a naval minefield.
I will now attempt to describe the two legal challenges noted above. The first of these is the possible susceptibility of the modern concept of ‘auxiliary’ to attempts to alter or water it down so as to reduce the LoNW rights differential as between warships and auxiliaries. The second concerns the status upon capture of shore-based autonomous auxiliary crews.
The modern concept of naval auxiliary is a creature of (quite) recent custom
The concept of auxiliary as now generally employed is of relatively recent provenance. The definition in the San Remo Manual (rule 13(h)) emerged from the widely subscribed drafting process for that Manual (including, for example, PRC experts and observers): ‘Auxiliary vessel means a vessel, other than a warship, that is owned by or under the exclusive control of the armed forces of a State and used for the time being on government non-commercial service’. It has since been widely replicated in national military manuals (eg, UK para 13.5). However, this clear differentiation from warships is quite recent. Older usages of the term ‘auxiliary’ included reference to merchant vessels converted into warships in accordance with 1907 Hague Convention VII (the origins of the modern definition of warship, which was specifically designed to ensure that privateering did not re-enter naval capability considerations – eg at pp772-773, 853, 920 etc, and also here). One example is the German ‘auxiliary cruisers’ referenced in the 1919 Treaty of Versailles (Article 187). Other treaties use the term auxiliary to denote ‘vessels of war’ that were not primarily fighting ships. One example is the 1936 Montreux Convention regarding the Turkish Straits (at Annex II.B(6)), although this treaty did specifically treat one category of naval auxiliaries – vessels carrying fuel – differently from other naval auxiliaries (Article 9). But the key point is that these formulations still categorised auxiliaries as ‘ships of war’, not as a distinct category of vessel. The separation between warships and auxiliaries as reflected in modern LoNW was arguably a result of, and enabled by, the 1958 and 1982 law of the sea conventions and the new concept of ‘state vessels on non-commercial service’ (see, 1958 High Seas Convention Article 9; 1958 Territorial Sea and Contiguous Zone Convention Article 22; 1982 LOSC Articles 31-32).
The challenge here is to recognise that because this modern LoNW concept of auxiliary is quite new, it is also still perhaps only thinly embedded. This makes it potentially susceptible to being unsettled if states wished to pursue this course of action. That is, there is still perhaps some room for development and refinement within this modern concept of auxiliary given that it is at best a creature of recent custom, and that it’s treaty appearances have traditionally not differentiated warships and auxiliaries in this way. This means that some states may, should their interests dictate, seek to walk back this ‘modern’ distinction, which has not yet been crystalised in treaty, so that they can employ auxiliaries in a greater range of belligerent conduct.
A key example of where and why this desire may arise is the day to day routine enforcement of a blockade or visit and search regime which – as a belligerent right – is currently permissible only for warships. Consequently, this relatively modern distinction has also made it newly necessary to better define the scope of ‘belligerent rights’ now that auxiliaries are no longer a subcategory of warships. The Newport Manual (§3.1) lists the belligerent rights exercisable only by warships (but not by auxiliaries) as including
‘the right to conduct hostilities; the right to visit, search, and diversion of enemy and neutral vessels; the right of capture; the right to inspect specially protected enemy vessels (e.g., hospital ships); the right to control neutral vessels and aircraft in the immediate vicinity of naval operations; the right to establish and enforce a blockade; the right to establish and enforce exclusion zones; the right to demand the surrender of enemy military personnel; and the right to undertake convoy operations.’
This is important, but not because of the targeting consequences of a breach – auxiliaries can be attacked in the same way as warships, so breach (an auxiliary employed as an ‘arsenal ship’ that fires containerised missile salvoes for example) does not create additional liabilities for auxiliaries or their crews. Nor is it significant due to the risk of perfidy, because an auxiliary that exercises belligerent rights is not feigning a status that invites belief in the adversary that the vessel is required to be treated differently – auxiliaries are already liable to attack just as warships are. Rather, as noted above, the limitation of belligerent rights to warships is really about vigilant policing against the reprise of privateering. But in creating the new category of non-warship auxiliaries, LoNW has also created the need to better define this new intermediate category of rights as noted above, precisely because auxiliary operational rights are understood to be less than warship belligerent rights, but more than merchant vessel defensive and resistance rights. The Newport Manual has sought to list an initial, state practice-based, set of auxiliary operational rights (§3.4). However, issues remain in this regard (eg, auxiliaries providing information into a ‘kill chain’) and these will sharpen as the increased desire to utilise auxiliaries in the face of redeployment of relatively scarce and expensive warships to solely fighting roles begins to bite in the event of IAC at sea.
Autonomous auxiliary control
A key legal challenge presented by the likely escalation in autonomous auxiliary vessel use is that the well-established PW status afforded to auxiliary crews (and also merchant vessel crews in many situations) is traditionally related to capture at sea / in the vessel. This means civilians directly participating in hostilities (DPH) / members of an organised armed group (OAG) are not relevant targeting or treatment assessment frameworks for auxiliary vessel crews (nor merchant vessel crews) under LoNW (see Newport Manual §10.6.3). This is because targeting and capture in LoNW is platform based, and the liabilities and treatment determinations relevant to the crew in this respect are also generally dictated by the status of the platform. But what if the civilian mariner crew and command of the autonomous auxiliary vessel are physically located in a control centre ashore, and the auxiliary is at the relevant time engaged in exercising permissible operational rights – eg refuelling an autonomous warship at sea, or landing military forces during an amphibious assault? In terms of targeting, the civilians DPH / auxiliary crew distinction does not have any practical implications because they are both liable to be made the object of attack. But the legal basis for the liability is different and needs to be recognised – civilians DPH are targetable in accordance with their conduct, while auxiliary crews are targetable due to the status of their platform.
However, if the auxiliary ‘crew’ were to be captured, there is a considerable potential difference in the applicable post-capture treatment regime. If the shore-based civilian controllers of the autonomous auxiliary are categorised as civilians DPH, they would have no access to PW status and treatment, nor to the quasi-combatant immunity that (at sea) follows from their auxiliary’s conduct in directly supporting military operations. But if they remain characterised as an auxiliary crew – albeit one that is not at sea in their platform, but rather controlling their auxiliary from ashore – then the (shore-based) captured crew (who were captured ashore) should still be entitled to PW status. It is my view that this second interpretation is the correct approach, because – whether at sea or ashore – the key issue is the platform (the autonomous auxiliary), its operations in its operational domain (exercising auxiliary operational rights at sea), and the applicable lex specialis (LoNW). However, this analysis is not without its own challenges: Consider, for example, the orthodox assessment that a non-mariner civilian guarding the door to the shore-based compartment from whence the autonomous auxiliary is controlled could be a civilian DPH; by contrast, the autonomous auxiliary crew sitting two metres away in the control room would be entitled to PW status. However, such parsing is not a new issue for LoNW which has long applied a similar distinction between (for example) resisting merchant vessel crews (who become PW), and combative passengers in the resisting merchant vessel, who may be liable to post-capture treatment as civilians DPH.
Conclusion
In the event of large scale combat operations at sea in the context of an IAC, it is inevitable that auxiliary vessel employment will quickly escalate as scarce warships are increasingly focussed upon fighting roles. However, there are some lingering issues in the law attending the employment of auxiliaries. One is the relative recency (and perhaps fragility?) of the concept as encapsulated in modern LoNW, along with the still emerging conception of auxiliary operational rights as a category of hostilities’ rights bracketed between warship belligerent rights and merchant vessel defensive / resistance rights. Another is potentially contested views as to the applicable treatment regime for captured shore-based autonomous auxiliary crews. These issues would certainly benefit from further analysis, and hopefully resolution – preferably before they need to be applied in an unfolding conflict at sea.
