Who Is at War? Becoming a Co-Party to an Armed Conflict

ASHLEY DEEKS: Thank you so much for coming. It's great to see such a good turnout here. I'm delighted today to introduce Alex Wenker, who is a senior research fellow at the Max Planck Institute for Comparative Public Law and International Law in Heidelberg, Germany. He also teaches at the Freie University of Berlin. It sounds better in the German, but I didn't have the courage to try it.

Holds an MJur and a doctorate of law from the University of Oxford, and a master's in law from Université Paris II-Panthéon-Assas. And perhaps most relevant to today's conversation, he is the author of a book called Party Status to Armed Conflict in International Law, which Oxford University Press just published, nice and pretty, based on his doctoral thesis, which received several prizes.

The book's general editors describe it as deeply researched, analytically rigorous, creative, and possessed of vision. And having read it myself, I agree with that assessment. I think it does a great job. Alex breaking down the question of how to identify co-parties to a conflict in very clear parts that bring the reader along with his analysis. So I very much commend it to you as a book.

He ultimately persuaded me that his proposed analytical framework is the most sensible way to think about this issue, and I think this will be the go to book on the question of co-party status for years to come. So the way we're going to proceed today, Alex is going to introduce and discuss the book's basic claims for about 15 to 20 minutes. I'll then ask him a few questions and we will open it up to questions from the audience. So with that, over to you, Alex.

ALEX WENTKER: Thank you very much, Ashley, for that very introduction and for the invitation to be here. It's a great pleasure and an honor. So probably the best way to illustrate what this book is about and why I think the book had to be written, are the public debates in many Western states that we've seen over support to Ukraine for the past, well, now almost three years.

From the very early days of that war, Western states have emphasized that they would not support Ukraine in a way that would make them parties to the conflict under international law. And in fact, that has been repeated over and over again, every more or less significant change in the assistance by different states has been sure to be framed in that language of party status.

And these debates on party status have, I think, shown that there is a need for reflection on the concept of party status, mainly on two fronts. So first, there has been, in these debates, ample confusion on what it means in legal terms to become a party to a conflict. So party status does get a lot of attention in the debates since 2022, though it seems that this is sometimes for the wrong reasons.

And conversely, some of the actual reasons why we should think about party status are being overlooked. And then secondly, there is uncertainty regarding how we can tell who is a party, so where that line is drawn, how it is crossed. And so this two-fold question is really what my book is about. It's about why it matters who is a party to an armed conflict and how we can tell.

Now, if I were to choose that topic today, it would probably be because of the discomfort with these debates and the confusion that I've just described. When I started thinking about the concept a couple of years ago, it was rather because I thought it hadn't received enough attention and it hadn't received enough attention, although there had been ample reason to think about it because it has proved an issue in many armed conflicts over the past years, past decades, even whether these conflicts were international or noninternational.

So why is party status so often a tricky issue? Well, that is because armed conflicts are often fought in cooperation between multiple states, armed groups, or international organizations with varying degrees of involvement. There are diverse patterns of cooperation, and these patterns are characteristic of modern armed conflict, and this is crucial, they make it challenging to identify who among the different cooperation partners will then qualify as a party.

At the same time, cooperation in armed conflict also raises particular risks regarding the protection of individuals, and these risks are due to the potential for diffused responsibilities that we see in such cooperation settings. And these are risks, which I think the law must address.

So what we need are really two things. First, we need a clear sense of how party status is relevant within the current regulation of armed conflict, and then secondly, we need legal criteria for identifying parties. And these criteria must be such that they address and can capture the complex cooperation patterns that we see in today's wars.

So to respond to that two-fold need for reflection, I have structured my book in the way that you can see here. So in the first part, I systematized the ways in which the international legal framework attaches relevance to the concept of party status. And the second part of the book, I then conceptualize the legal criteria which must be fulfilled to establish that an entity is a party to an armed conflict under international law.

So let me then briefly sketch how I develop my argument over these two main parts of the book. First, regarding the legal meaning and relevance of the concept of party status. This is part 1 consisting of chapters 1 and 2. Again, to illustrate, if we look at the political debates in Western states regarding Ukraine, I think that party status has featured so prominently, partly because of the political implications that it would have for Western states to be at war with Russia.

At the same time, there seems to have been a common perception and an underlying assumption that being a party alongside Ukraine would somehow entitle Russia to use force against Western states, and that legal connotation, in addition, again, to the political considerations. That legal connotation of party status, I think is somewhat reminiscent of the meaning of being in a state of war in traditional international law.

So the idea was that war was a separate sphere from peace, and in that sphere, the contestants were allowed to bring each other down by force. Now, that is, of course, difficult to square with how international law today regulates war, where chiefly we have the prohibition of the use of force, and that prohibition also applies between parties to an international armed conflict, so I would argue at least.

And states also remain bound, for example, by human rights law. All that to say that being a party today certainly does not put the belligerents in a separate legal sphere any longer. And in practical terms, that would mean that Russia, for example, would commit further violations of the use ad bellum if it were to attack Western states, even if these states were to be or become parties to the conflict.

So the blurring of the traditional spheres of war and peace in international law, that is one of the wider developments that I think calls us to reexamine what party status means today. A second such wider development is the humanisation and the individualization of international law and war because that is the development that calls for repositioning the place of the collective entities between whom war is fought, that is, the parties.

And then the third such development is that war is increasingly regulated as a concern to the international community as a whole, rather than just between two parties, as dualists as it were.

So against that background of these three wider shifts in the international legal order and international legal thought, what I try to do in chapters 1 and 2 is to show that party status is still a crucial legal concept, and that is because the international legal regulation of armed conflict is in many respects organized around the parties, and party status. So at one level, the parties bear central sets of obligations under IHL, both regarding the conduct of hostilities and regarding the protection of individuals.

And then next to duties, party status traditionally also came with belligerent rights. That is somewhat a more complicated category today because the permissions that flow from party status today cannot be such that they can grant permission to use force beyond what the use ad bellum permits.

Then, in addition to being addressees of international law themselves, the protection rights, duties, and responsibilities of other addressees of international law in armed conflict, they're also determined by reference to the parties. Now by other addresses I mean individuals and third states, that is, states that are not parties to the conflict.

For individuals, it is the nature of their connection to the parties that determines, for example, whether they qualify as combatants or as members of specially protected groups of persons. And a connection to the parties also matters for establishing international criminal responsibility for war crimes, for example, as part of assessing the indicators that are used for the Nexus requirement.

For third states and their legal relationship with the parties, it also matters to know who is a party and who not. And that is not only so for the traditional law of neutrality, body of law that specifically aim to apply between third states and the parties. But it's also true, for example, if the duty under Common Article I to the Geneva Conventions the duty not to provide assistance to IHL violations by the parties.

So it is really in the relationship to these other addresses that party status has some of its central legal significance. In other words, the angle of party status helps us seeing how these other addresses are integrated into the regulation of armed conflict. And conceptually, it therefore helps understand the wider shifts in how international law regulates war that I've mentioned earlier, and how these actually play out.

More widely what I think the importance of party status as a regulatory concept suggests is that the concept helps us to better grasp the structure of the regulation of armed conflict as a whole. So in the buildup of the argument, part 1 of the book gives a sense of the ways in which it matters in legal terms to identify the parties. And then on that foundation, I develop my account of the legal framework for identifying parties, this is part 2 of the book.

And I do so with a focus on those conflicts where it's mainly relevant and challenging to identify parties because there are multiple potential parties on one or both sides of the conflict. And I call these co-parties in multiparty conflicts. In a nutshell, the structure of the law of armed conflict, if we read it in light of past practice, suggests two criteria plus one specification.

So to become a party to an armed conflict, a state or an international organization, or an armed group must first carry out acts with a direct connection to hostilities. And secondly, that contribution must be closely coordinated with the other party or parties on the same side of the conflict. And the specification is that these two criteria presuppose that you act knowingly.

So let me briefly walk you through these elements. The first criterion, the direct connection to hostilities, well, that relates to the nature of the acts. Very basically, of course, speaking of acts of a state, an IO, an armed group that is a collective entity that presumes that the acts of certain individuals can be attributed to that potential co-party.

And then regarding more specifically, the quality of the act, I found quite solid evidence in state practice and opinio juris that a potential co-party need not on its own perform acts that will suffice to create armed conflict an IAC or a NIAC in the first place, as long as the acts of all co-parties taken together do so. Still hostilities are the essence of the conflict relationship between the parties.

And structurally therefore, the acts of an entity must form part of these hostilities for it to become a party. Hostilities can be defined broadly as acts which cause harm to the adverse armed forces. So I think it makes sense to require that the acts of the state have a direct connection to harm to the adversary. And as I have found that also resonates with how states have understood the contours of party status in past armed conflicts.

Now, what exactly a direct connection means is not entirely settled. To my mind, a practical way forward is to rely on how the ICRC has understood the element of a direct causation of harm in the context of direct participation of civilians in hostilities. That would then mean that the acts of a state must cause harm to the adversary in one causal step, or form part of an integral part of coordinated military operations that do so.

The second criterion then concerns the character of the relationship between parties on the same side, i.e. co-parties. It's not enough for states or IOs or armed groups to simply fight a common enemy simultaneously because after all one state or IO armed group can very well be involved in multiple conflicts at the same time, and these can be separate conflicts that had nothing to do with one another.

So what ties the acts of multiple entities together so that they can be considered co-parties is, in fact, the fact that they coordinate their military operations in a way that they build on one another as part of one armed conflict. Now, the exact degree of coordination is hard to pin down. At Chatham House we took a relatively flexible approach.

In my book I've tried to make it somewhat more specific and to make a more narrow proposal. I'm happy to explain that further in the Q&A in the interest of time. Now, if we have a direct connection to hostilities, insufficient coordination with fellow co-parties, then the party status of that state does not depend on whether the state wants to be a party or not.

Now, this does not mean that the state needs to intend or know the legal consequences of its act with respect to party status, leaving aside perhaps, the situation of declarations of war. So no subjective element is required with respect to legal consequences, but I do think that states need to be aware of the relevant facts. And I think that, that subjective dimension of knowledge is actually inherent in the very notion of making a sufficiently coordinated contribution with a direct connection to hostilities.

So to illustrate how the criteria may operate, let's just very briefly consider different types of military assistance that we've seen in the war against Ukraine. So supplying weapons, regardless of what kind, does not have a sufficiently direct connection to hostilities. The same is true of training provided to Ukrainian troops because it's only the actual use of the weapons or of the trained skills that directly cause harm to Russia and thus form part of military operations.

The matter may be different regarding intelligence cooperation. It has been reported, for example, that the US has provided real time intelligence on specific targets, and that localization and verification of targets can be part of the wider targeting process and thus of a concrete military operation.

And the reports also suggest that, that was in close coordination with the operational decision making processes of Ukraine, and that the US has been aware of the role of its intelligence. So here, to the extent that, that is true, we may well get pretty close to party status.

In terms of method, taking a step back, I've tried to discern these criteria from the structure of the system of the legal regulation of armed conflict. So by way of systemic interpretation and for that systemic interpretation, I also draw on the analysis in part 1 of the book on the position that the parties hold within the international legal regulation of armed conflict.

But then I've also tried to show how the criteria that I discern resonate with how party status has been understood in the practice of states and IOs in past and ongoing armed conflicts. So in that sense, if you will, I've tried to build the account deductively, but then confirmed it inductively with the material available.

And what I put forward in the book attempts to be a common analytical framework that purports to capture all scenarios in which issues of identifying co-parties arise. And ideally, that framework should also be readily applicable by all those that need to assess who is a party to an armed conflict in a particular conflict setting.

And to make the findings of the book more useful in practice, they have fed into a Chatham House research paper based on discussions with legal advisors from a number of states and IOs. Then in the final step, and this is chapter 5 of the book, I draw out some key implications from the co-party framework, implications for how international law allocates obligations in armed conflict.

And specifically I show that co-parties spare particular positive duties flowing from their code party status, and these duties are owed regarding the acts of their fellow co-parties in armed conflict. And they go beyond what third states would need to do to ensure that the parties don't commit violations of IHL.

And what I try to show here is that the cooperative patents that make you a party or a co-party in the first place, they can also be avenues then for ensuring the legal protection of individuals in armed conflict. So in sum, I hope that through the lens of the concept of party status, the book can contribute in some small way to a clearer understanding of how the structures of international law in this field can respond to the challenges of cooperation in armed conflict. And I'm looking forward to the discussion. Thank you.

ASHLEY DEEKS: Alex, thanks so much. That was really great. An excellent summary of your excellent book. I have a number of questions. We have a big audience, so I don't want to monopolize them, but I could ask you questions for about an hour.

So let me just flag a few. I want to start with a point you made really early on, and you make early in your book that this has been a very underexplored area, especially by lawyers. And I wonder if you had thoughts about why that's so when we have so often states fighting in coalitions?

ALEX WENTKER: Well, that's a good question on which ultimately, of course, I don't exactly know the answer. I can only speculate. And I think that one of the reasons may have been that there has been a lot of focus on the status of armed conflict and on classification. And I think the scholarly debate has focused so heavily on that, that they may have distracted us from other questions.

If you think that conflict classification is something that is incredibly important, and it's the first thing that you consider when thinking about an armed conflict. It makes you perhaps overlook that there may be follow up questions. So that's perhaps, my best guess on why it hasn't featured as prominently enough.

But as I said at the beginning of my research, I had that perception myself. And I did not necessarily always, when talking to colleagues, have the impression that they would necessarily see the implications. So it wasn't at the time a shared sense, not nearly as shared as now that such scholarship is needed.

ASHLEY DEEKS: Great. Thanks. Another issue you touched on briefly is neutrality law and one thing you think about is the extent to which states that are not a party to a given conflict are bound by neutrality law, does it structure their behavior? And there's been quite a lot of debate in the past 10 years, especially whether the law of neutrality actually survives the existence of the UN Charter.

I wonder if you could explain why the existence of the charter raises this question about the durability of the law of neutrality. And I think you ultimately conclude that the law of neutrality remains relevant today, if you could just say a little bit about why.

ALEX WENTKER: No, really interesting question. So I think the first line of an answer is neutrality law remains relevant because states are just not ready yet to let go of it, it seems. So we do have evidence in practice of neutrality remaining relevant throughout pretty much all major international armed conflicts since World War II, Ukraine being somewhat of an exception rather than the rule.

But there are many explanations for why neutrality hasn't featured that prominently in this conflict that do not presuppose that neutrality has become irrelevant, but rather that it's just politically entirely inopportune at this point in time for many states to claim neutrality regarding Ukraine. And just to illustrate how neutrality states consider neutrality to be relevant, think of states positions regarding cyberspace.

And even there, you have a couple of states that, in their positions on how international law applies in cyberspace, clearly set out that they think neutrality law is one of the bodies of law that is to regulate that sphere, which is quite interesting if you consider how old that body of law is and what it was originally made to do. So there is something.

Admittedly, the evidence does not suggest that neutrality is always at the front line. It probably has never been. It wasn't intended to be. But it's there, I'd say, somewhat beneath the surface, and states like to get back to it at times, like to keep it there for whenever the occasion arises.

So that's the practical argument, which is, of course, relevant from the perspective of the sources. And it's very hard to make an argument anyway that a rule of international law has died. So there's that. But then you also mentioned the difficulty of well, if neutrality law is still around as a matter of fact of practice, how do we square it with the contemporary law on peace and security, chiefly the UN Charter framework?

And that is not so trivial, but I think it's possible. So, yes, the Security Council may override neutrality law if and to the extent that the Security Council not only authorizes, but obliges states to act in a certain conflict by giving assistance to one of the parties to the conflict in violation of neutrality law. Where that happens, that obligation under Article 103 of the UN Charter would override.

So the obligation to follow the Security Council resolution would override the neutrality obligation running counter to that. But these are only very rare cases because it presupposes first that the Council not only authorizes, but obliges, and more often it only authorizes. And it also presupposes that the obligation or the thing that the Council requires you to do, requires you to deviate from neutrality law, which is often not the case.

There's many things you can do that do not violate neutrality law. So there is lots of room to square it with that. We may consider if the Council doesn't act, how can you square a situation such as Ukraine where states provide assistance to the victim of war of aggression, the victim of an armed attack, if you will?

And there again, I think it's reasonable to say, well, neutrality law exists, but where it conflicts with basic premises of the US ad bellum such as self-defense, must be effective. Well, there it can be superseded and we can argue that there is an exception from these neutrality duties, so that assistance to self-defense can be given.

ASHLEY DEEKS: Excellent. If we can just talk briefly, you mentioned your methodology and one of the things that I think becomes clear in the book is that you've had to conduct your analysis and to try to draw conclusions on relatively limited state practice, relatively few statements that states actually make about what they're doing. And so I guess I'm wondering how you would describe the quality of the framework that you set out here.

Do you see it as you're actually trying to describe what you think customary international law is about the framework? Is it just a descriptive sense of what you think states thing the law might be? Is it normative? How would you characterize the framework that your book ultimately puts forward?

ALEX WENTKER: Important question. And I would say, in short, I'd characterize this as my two sentence on what the law is and how it can be understood. So it's of course, not just a restatement of the law, but also provides my reasoning on why that is so and on how it can be understood.

How did I get there? As you rightly mentioned, practice is scarce and limited on many questions, at least and some I had better evidence than on others. So the difficulty was that obviously there must be a concept of what it means to be a party, and most specifically also how you become a party, what are the criteria?

There must be one because the treaties use the term parties to the conflict all the time. They just don't tell us how you become a party, but there is something that is implicit in there. Now, I didn't have enough practice and opinio juris to establish a customary rule specifically for that purpose. But what I think I could do was to say, well, what do the treaties have in mind and the customary rules when they refer to parties to the conflict?

And that in a sense implied an exercise of deduction. So what do the treaties envision when they talk about parties? Well, they have in mind that the parties are central actors, that they have all these obligations, perhaps rights that everything depends on them as I showed in the first part of the book.

And then I try to draw conclusions from that deductively. And I think that is, I mean, it's also how the ICJ often arrives at conclusions on what the law is in a certain point. You can't only induce, you can also deduce because then the rule is there. It's implicit in the rules that we have and states consent has been given to those rules. So I'm not making different proposals.

And once you arrive at a certain result by deduction, I think it just makes sense to try and test that inductively and try and confirm with that material that you have that may not suffice in the first place, but still gives you a hold there. And that's actually also with the ICJ again pretty often does, it's a flexible mixing of deduction and induction. And I found that to be sound.

ASHLEY DEEKS: Great. I was not trying to suggest by my question that it was not sound. I was just trying to sharpen the nature of the claim. You have spoken a little bit about the Russia-Ukraine conflict and I wanted to work through with you a couple of other real world co-party questions to see how you think about it.

I think you concluded in your book and in your comments here that the United States may actually be a co-party to Ukraine in the ongoing conflict. I wanted to ask, there was reporting that the US had provided intelligence to Israel about where members of Hamas in Gaza were hiding. And so I'm curious, in your view, whether that assistance rendered the United States a party to the conflict between Israel and Hamas, and if so what legal implications follow?

And also North Korea's provision of soldiers to Russia in the Ukraine conflict and the presence of those soldiers actually on I think, Ukrainian territory at this point. Can you help us think through how your co-party analysis applies there?

ALEX WENTKER: Yeah. So if and to the extent that the US really provides the coordinates for specific targets to Israel as part of concrete military operations similar to what has been reported they're doing in Ukraine, if it's really that, then I think we could take the first box of a direct connection to hostilities. And I think you'd have to assume that, that would also happen in very close coordination with the Israelis.

So that's for the second requirement. For Ukraine, there has been reporting that the Ukrainians wouldn't actually engage a target without US confirmation if they could have that intelligence. So there was a particularly strong involvement of the US also, I'd say, in the decision making process really, on these military operations.

Again, that would be a factual question here to what extent that would be true to bolster the closeness of the coordination, if you will. But I think a reasonable case could be made to the extent that, that is true, which the US probably will deny at this stage. But of course, if it looks very similar to what we've seen in Ukraine, then similar analysis would apply, I think.

And regarding North Korea, I think the case regarding the my two elements is even easier because obviously North Korea has been fighting on the ground. So there's a direct connection to hostilities that was immensely coordinated with Russia to the point that they've been camouflaged as certain parts of the Russian armed forces. And you can assume that the coordination requirement has been met.

The difficulty there was rather really at the previous stage. We don't have that on any longer. But if you remember, I briefly talked about attribution as something that is normally implicit when a soldier fights as a member of the armed forces that is attributable to its state. But here that can be difficult to see. Well, who is it that these soldiers are fighting for?

And it could theoretically be the case that North Korea was lending these armed forces as a state organ, lending it to Russia, which would then mean that it would exclusively be attributable to Russia, and North Korea would not become a party in its own right. I would say that the threshold for that organ lending is not met because it would mean that Russia would be in exclusive control. And I cannot imagine that North Korea has, in effect, cut all lines of command and control to these soldiers.

They seem to be North Korean generals over there. I don't suppose that just receiving orders from Putin, but also from Kim. And to the extent that is the case, I think the more likely scenario is that it's in fact attributable to both states. And that would suffice for North Korea to become a party in its own right alongside Russia.

ASHLEY DEEKS: Your book outlines a couple of key reasons why it's critical to understand whether a state is, in fact, a co-party to a given conflict. And you touched on that in your comments. You said that being a co-party basically imposes on you more obligations to your fellow co-party than it would on a third state. I wonder if you could take a little bit of a deeper dive into some of the implications that come along with becoming a co-party, or being a co-party to a conflict vis a vis your other partners?

ALEX WENTKER: Yeah, very relevant and important. So I make the case in the final chapter of the book that you have greater obligations and they're relevant mainly along two fronts. So first, we have the conduct of hostilities, and then, I mean analytically, we can split it like that, conduct of hostilities, protection of individuals.

Now, what does that mean? Well, the parties, for example, have obligations to take precautions in attack, but also more widely in all military operations that they undertake. And I think if you're a co-party alongside others, precautions relate to your coordinated military operations with others.

Well, then you must, as part of your precautions, which are do everything you can to spare civilians, and that's then specified. You must also take steps so that your partners also spare civilians to the extent that is militarily feasible. So that's just one illustration in the field of conduct of hostilities.

And if you think of the protection of individual side there, for example, the parties have other positive obligations that include doing everything that is feasible to care for certain protected groups, care for the wounded and sick, look after the missing and the dead. Again, all framed in a positive due diligence manner, requiring you to do whatever you can.

And doing whatever you can as a co-party, I think also includes doing whatever you can so that your partners also do that. So it doubles up the obligation and creates that. What I think can be seen as a stronger web network of obligations.

And I think it's stronger by comparison to, and that should be explained, to Common Article I, which is the obligation that all states have, that all states that are parties to the Geneva Conventions, which means pretty much all states. All states must ensure respect for international humanitarian law, and that is being understood by some as an obligation to also take positive steps vis a vis the parties.

And if you push that argument very far, you could say, well, does it really make any difference whether you're a third state or a party? And I would say it does, first because that reading of Common Article I is still controversial, so it adds legal certainty. But it also, I think, adds specificity because even if it is true, the obligation and obligation that is framed in such relatively vague terms, I don't think that it provides good grounds for very specific conduct that is required.

While all these party obligations that we have, well, they are pretty specific. And relying on them therefore also gives us much more granularity.