The Attack on Syria and the Contemporary Jus ad Bellum

Written by

The United States, Britain, and France have attacked various chemical weapons facilities in Syria. Even before they acted, a number of commentators claimed that any such attack would be internationally unlawful. Below, I explain why that claim is too simplistic and how we should situate the operation in the jus ad bellum going forward. Let me say at the outset that I don’t support this operation and have serious doubts about the capacity of the United States, in particular, to implement a coherent policy in Syria. (I also think the operation violates U.S. law.) So, I’m not arguing that the operation was a good idea or even that it should be lawful. I’m making an analytic argument about how the jus ad bellum works.

The April 2017 Incident

This was not the first attack against Syria for its use of chemical weapons. In April 2017, the United States struck Syria for the same asserted reason: as a reprisal for the regime’s use of chemical weapons in violation of international law. At the time, most commentators said that the U.S. operation was unlawful. It was inconsistent with the longstanding interpretation of Article 2(4) of the UN Charter and not covered by the Charter exceptions. Assad didn’t consent to the operation, the Security Council hadn’t authorized it, and it wasn’t taken in self-defense.

There is an ongoing debate about whether the jus ad bellum contains another exception for humanitarian interventions. The dominant view is that it does not. States (as a group) have periodically condoned unilateral operations that can be labeled “humanitarian,” but the vast majority of them have declined to support a generally applicable humanitarian exception to 2(4). They have instead insisted that no such exception exists. Further, even if there were one, its application to the 2017 operation would have been dubious. The operation looked more like a reprisal than like what we usually mean by a “humanitarian intervention.” President Trump said that it was designed “to prevent and deter the spread and use of deadly chemical weapons,” not to avert the many other atrocities that were being committed in Syria. Forcible reprisals are by almost all accounts unlawful.

So, it would be hard to show that the 2017 operation was consistent with the formal legal doctrine on the use of force. For a sophisticated analysis of why, see the latest piece by Jack Goldsmith and Oona Hathaway at Lawfare. I think Jack and Oona are basically right as far as the doctrine goes. But I also think the doctrine doesn’t get us very far. We know that, in the jus ad bellum, as in other areas of international law, the formal legal doctrine is at times dissociated from the law’s operation. If we want to describe or understand how the law actually plays out in concrete cases, we have to go beyond it.

And when we do, we see something that might be surprising. States broadly condoned the 2017 operation against Syria. Eleven states expressly endorsed it at the UN Security Council the next day: Australia, France, Germany, Italy, the Netherlands, New Zealand, Saudi Arabia, Turkey, the United Kingdom, and Ukraine. Several other states — Canada, Israel, Poland, Qatar, the UAE, Bahrain, Kuwait, Jordan, and Spain—supported the U.S. operation in alternative arenas. So did the European Union. A different group of states, including China, expressed ambivalence about the U.S. operation; these states neither supported nor criticized what the United States had done. Only a small handful of states, including Iran, Syria, and Russia, expressly condemned the operation as unlawful.

The 2017 incident thus was not a case in which one state discretely uses force and others look the other way. The United States publicly owned what it did. The Security Council met to discuss it. Many other states affirmatively supported it. And very few states were willing even to say that it was unlawful. Here, states (as a group) made a decision on the law; they decided to deprive Article 2(4) of both its operational relevance and its normative bite. That looks a lot like deciding to make the operation lawful.

I say “looks like,” because I’m not arguing that the 2017 operation was actually lawful. As discussed, I don’t think it satisfied the formal legal doctrine. But I also don’t think that ends the legal inquiry. The jus ad bellum consists of more than just the doctrinal standards. It consists of a broader set of social institutions, practices, and expectations. So, in my view, the lawfulness of the 2017 operation is an open question and less clear-cut than the formalist doctrine would suggest. What’s significant is that almost every state acted as if, or almost as if, the 2017 operation was lawful.

A Legal Precedent?

Of course, any incident can be a precedent in the sense that it happened. The critical question is to what extent states may rely on it to justify a subsequent operation, like the one that the United States, the United Kingdom, and France undertook on Friday night.

Two responses to that question are common and, in my view, not compelling. One goes something like this: the 2017 incident is not legally relevant because it occurred entirely outside of and in contempt of the law. To take this claim seriously, one would have to accept that the vast majority of states openly disregarded the law in 2017, that many of them publicly defended their insubordination at the very institution that is legally charged with assessing this conduct, and that nothing happened in response. Those who have advanced this claim have not offered an account of why states bothered to go to the Council and endorse the U.S. operation, if they were acting outside the law, or why the best interpretation of what they were doing at the Council — when they were explaining their decisions not to apply Article 2(4) — is practicing not law but a kind of politics that is antithetical to law. I do not find that argument persuasive. But even if it were, its implications would be profound: it would suggest that the jus ad bellum is irrelevant not just to the United States but also to the Security Council and the many states that endorsed or supported, in one way or another, the U.S. action in 2017. It would also suggest that, in 2018, states that wanted to use force in Syria could do so without giving the law much thought.

A second response is to read the 2017 incident as evidence that the legal doctrine is not as I have described it — to say that the jus ad bellum actually contains or is developing a formal exception to Article 2(4) for cases like the 2017 operation. A few scholars took this position at the time. They suggested that there is or might be a general standard that licenses force in an entire category of cases (however that category is defined). The problem with this position is that it distorts what states did in 2017. They clearly signaled that their support for the U.S. operation was contingent on the facts and not a reliable indicator of how they would respond in the future. The reaction was meant to be fact-specific—to condone one operation, without purporting to apply or establish a standard of general applicability.

That tactic is not new and sometimes works. Unlike a general standard, which automatically applies to and helps justify every operation that falls within its scope, a fact-specific decision is designed only for the case at hand. The reaction in 2017 was not meant to be controlling in or a sufficient justification for any subsequent operation. The problem is that the facts in Syria in 2018 almost replicate those from 2017. In both cases, limited, targeted air strikes were launched after the Security Council failed to take meaningful action in response to reports that the Assad regime used chemical weapons against its own people. So, the precedent is directly on point. It is very good evidence of states’ expectations and normative priorities for this situation.

And, indeed, it largely foreshadowed the reaction to the latest attack. Despite the views of many international lawyers on Twitter and elsewhere, it is striking how many states have once again condoned or supported the operation against Syria for its use of chemical weapons. According to news reports, only three states — Russia, China, and Bolivia — backed a draft Security Council resolution that would have condemned the operation as an act of aggression. Eight states voted against the resolution, and four states abstained on it.

Appraising the 2018 Operation (and the Jus ad Bellum)

Though the pattern from 2017 seems to have carried over, it is still too early to know what to make of the 2018 operation or what it reveals for the jus ad bellum going forward. But for now, I want to leave you with five takeaway points.

First, the fact that the jus ad bellum did not constrain the states that used force against Syria does not mean that it was irrelevant. Although the modern jus ad bellum is often described as an instrument of peace and a constraint on cross-border force, it has always also facilitated some force. When it licenses force, it legitimizes that conduct in law. In these circumstances, it makes force easier to execute and more difficult to challenge than it otherwise would be. This means that the jus ad bellum can be relevant and effective even when it does not inhibit states from taking or supporting legally dubious operations. It might still confer legitimacy on or deny legitimacy to a given operation. For the operations in Syria, the jus ad bellum put the states that wanted to use force in the position of having to work to legitimize their conduct. Of course, these states might not have cared about their legitimacy, but they seemed to. Both in 2017 and in 2018, they expended considerable energy building a case for themselves at the Security Council.

Second, the fact that states have not defended the operation in expressly legal terms does not mean that their justifications are outside of law. As far as I know, the United Kingdom is the only state that has justified the 2018 operation in explicitly legal terms. It is one of the few states that recognizes a humanitarian exception to Article 2(4) and has invoked that exception here. By contrast, in 2017, the United States presented a set of case-specific considerations that, in its view, warranted the use of force. It did not expressly assert that it was acting lawfully. Neither did the states that supported it. I suspect that the United States and most other states will follow a similar script in 2018.

Some international lawyers have interpreted that to mean that the United States and its supporters did not present a legal justification for the 2017 operation. This position assumes that a justification is “legal” only if it expressly invokes a variant of the word “law” or relies on the formal doctrine. I think that position misunderstand how states engage with the jus ad vellum — that thus how the jus ad bellum actually operates — in cases like these. In 2017 and today, the United States and other states that have supported it have made claims on the law. They have argued, if only implicitly, against the application of Article 2(4). They have argued that the legal prohibition of chemical weapons is nearly sacrosanct and can, in certain circumstances, justify a forcible response. These are arguments about the law.

Third, if the reactions in 2018 look like the ones in 2017, it would not be evidence that states recognize or want to create an exception to Article 2(4) for an entire category of humanitarian interventions or reprisals. They plainly do not. States are balancing a number of competing considerations and have decided that not applying Article 2(4) was preferable to the alternatives in these cases.

Fourth, given the conflicting messages that states themselves are communicating, the best answer to the question of whether the two operations are lawful is not a simple “yes” or “no.” Such answers contain an element of advocacy; claims of legality or illegality are normative statements dressed up as descriptive ones. In my view, the answer to that question has to be more nuanced, contingent, and qualified.

Finally, these sorts of decisions rightly raise slippery slope concerns. If the United States and its friends may use force unilaterally when they please, what’s to stop other states from doing the same? I begin to tackle that question in my forthcoming article. For now, it’s worth keeping in mind that the jus ad bellum has never worked as it was originally intended. The challenge has always been to find ways to maintain its relevance and normative salience in a deeply imperfect world. As I intimated here and elaborate on in my article, the best way to preserve its regulatory purchase in today’s security environment is almost certainly not to squeeze, into the four corners of the formal legal doctrine, every operation that states choose to conduct, tolerate, and support. The gap between the formal doctrine and this practice might be unsatisfying, but it is not necessarily dysfunctional — or worse than the available alternatives.

Print Friendly, PDF & Email


Leave a Comment

Comments for this post are closed


Prof. Kevin Heller says

April 15, 2018

The problem with this post can be encapsulated in this sentence: "And very few states were willing even to say that it was unlawful." That may be true, but its importance is vastly outweighed by what Monica ignores: no state was willing to say that it was lawful, not even the state that engaged in it. Monica thus completely inverts the rule articulated in Nicaragua, arguing that a state that is trying to modify a customary rule has no duty to articulate the legal rationale behind its act (or even claim that the act was lawful), while states that oppose modification have a duty to condemn that act as unlawful. That is not how customary international law changes, for reasons Marko articulates beautifully above.

This sentence, concerning the 2017 attack, also completely undermines Monica's argument: "The reaction was meant to be fact-specific—to condone one operation, without purporting to apply or establish a standard of general applicability." Differently put: states were not trying to articulate a new rule of customary international law, which is literally by definition "a standard of general applicability." It is incoherent to argue that the 2017 attack was not designed to establish a legal rule but is still a precedent for the rule that the attack was not designed to establish. So once again the argument that the 2017 attack modified custom necessarily fails.

The basic flaw with Monica's argument is that she simply assumes states never use force knowing that neither the UN Charter nor customary international law permits them to do so. In her view, if states condoned the 2017 and 2018 attacks, that means they believed the attacks were lawful. ("In 2017 and today, the United States and other states that have supported it have made claims on the law. They have argued, if only implicitly, against the application of Article 2(4).") It is that view that is not "how the jus ad bellum actually operates" -- as the Kosovo example indicates with remarkable clarity.

Alessandra Asteriti says

April 15, 2018

Great post, although I disagree both with premises and with conclusions drawn. But my question is whether you really do not envision any role at all for the jus cogens status of the prohibition against the use of force. Is it really a rule like any other, that can be displaced and modified just like any other rule of customary international law, in fact, even more so? Where even the random acts of an irresponsible, supremely ignorant and dangerously authoritarian president, effected without any attempt of legal justification, have the same value as thought-out policy backed by legal argument? I am sorry about going on about this, but the normalisation of the pathological cannot be allowed to stand.

Adil Haque says

April 15, 2018

Hi Monica,

I look forward to reading your article! In the meantime, it might be helpful to distinguish between two claims:

A. These strikes violate the primary rules of international law. However, the international legal system is not exhausted by its primary rules. Decisions not to enforce the primary rules or "adjudicate" their violation may be politically motivated, but they are legal decisions (of a kind). Any description of international law that ignores these decisions, or dismisses them as merely political, is incomplete and misleading.
B. Decisions not to enforce the primary rules or "adjudicate" their violation can modify the primary rules even if that is not the intent (stated or unstated) of the relevant decision-makers and even if the secondary rules of international law do not provide for this method of changing the primary rules.

Claim A seems plausible enough. It’s claim B that gives me trouble. It’s not actually legal for police officers in the U.S. to kill unarmed African-American men who clearly pose no imminent threat to anyone. At the same time, any legal analysis of the use of deadly force by police officers that failed to mention patterns of non-enforcement would be deficient.

That’s it. Enjoy your Sunday,


Monica Hakimi says

April 16, 2018

Thanks to all of you for your comments.

Kevin, Marko, and many of my other critics are mostly arguing past me. I agree with them that the strikes against Syria did not satisfy the formal legal doctrine on the use of force. By this I mean (and I take them to mean) that the operation was inconsistent with Article 2(4) and did not satisfy any of the accepted exceptions to 2(4).

Likewise, we agree that (with the exception of the UK) the states that conducted or supported this operation do not want to change the doctrine. Even if they do, they almost certainly have not done enough to institute a change. In other words, they haven't created a new, generally applicable exception to 2(4). Kevin, you seem to misread me on this point. I'm not arguing that the doctrine is or is becoming other than what you say.

(As an aside, to answer Allessandra's question: one reason the doctrine is fairly resistant to change -- and can withstand operations like this one -- is that the jus cogens principle provides a stop-gap. So, that's part of the work that I think jus cogens is doing.)

For my critics, all of this means that states are acting outside of and in contempt of the law. In other words, they posit that the doctrine alone defines the law and that any act that is inconsistent with it is unlawful -- end stop. Their approach is not necessarily wrong, but it reflects a very cramped vision of what law (and particularly, of what the jus ad bellum) is. So, it doesn't help us understand how the law, which is not just a set of rules but rather a complicated social phenomenon, is playing out.

Adil's Option (A) gets at what I'm saying: when we ask, "what is the law?" we want to know more than just "how would an international court adjudicate whether this conduct is wrongful?" We want to know how the full range of politically relevant actors engage with the law when deciding whether to conduct, support, tolerate, or condemn the conduct. To what extent will they use legal language to legitimize or delegitimize it? In what arenas, if any, will they try to enforce their claims on the law? Will they publicly justify their conduct in terms that purport to reflect only to their own interests but the interests of the broader group? What institutions and processes will they use? And so on.

The doctrine alone is insufficient answer these questions. Worse, relying entirely on it will often be misleading and obscurant. It will suggest that the answers to those questions should be one thing, when in fact states themselves act like it is something else. And then, having defined the law in such a cramped way, my critics cannot help but to conclude that it is entirely irrelevant -- that states are acting in disregard of it. Of course, they sometimes do. I'm not saying (per Kevin) that states never intentionally violate the jus ad bellum. I'm just saying that the claim of "clear illegality" doesn't fully capture how they are engaging with the law in this case.

Dan Joyner says

April 16, 2018

This piece and the responses to it seem to me to perfectly illustrate the longstanding divide between American legal realism and European legal formalism. And Monica is right that the sides do often talk past each other. As a formalist myself, this piece makes my bones hurt. That's no slight on the quality of the piece, it just means that I view international law very differently than Monica, and it's difficult to get past those very different initial operating assumptions to have a meaningful exchange. Somewhere Anthea Roberts is selling a few more copies of her book because of this exchange.

Dan Joyner says

April 17, 2018

Hi Monica,
You mentioned on Twitter that you “resist” the label of legal realist. I certainly meant it here not as an insult, but as a collegial observation. And labels are dangerous and imprecise, it’s true. They frequently don’t do justice to the nuance of one’s position. But you say in your piece that you are making an “analytic argument about how the jus ad bellum works.” This of course raises the question of what the jus ad bellum is. You write that “The jus ad bellum consists of more than just the doctrinal standards. It consists of a broader set of social institutions, practices, and expectations.” This is, of course, where there is a pretty clean break from formalism in your analysis. To me, what you are examining in this piece is not in fact how the jus ad bellum works, because I do think that the jus ad bellum is essentially circumscribed by the formal doctrines and principles of international law, and I don’t include within that definition “social institutions, practices, and expectations.” So to me, what you are analyzing in this piece is not the question of how the jus ad bellum works, but rather the questions of how and why certain states have acted, and how relevant if at all the jus ad bellum, as an independent variable, was to those actions. To me this is a perfectly plausible IR theory question to ask. But it’s not essentially a legal question. And this is why I thought using the term “realist” might be parsimonious in describing your position, because looking at international law through the lens of international relations theory is a well-established element of American legal realism. Again, none of this is meant as a criticism of your analysis within, as I see it, its proper IR context. It’s simply an observation that to me, as a legal formalist, your analysis is not actually about how the law works internally, but rather about how states act externally relative to the law.
Best wishes,

Aurel Sari says

April 17, 2018

Dan, another binary that describes the difference you touch upon is the occupational divide between legal practice and legal scholarship. The practitioner, typically, wants to know how the law works in order to assess risk and offer advice. The scholar, typically, wants to know what the law is. Both deal with legal questions: one from a factual perspective, the other from a normative one.

Before anyone objects: yes, these are merely stereotypes with all their limitations, but also, I think, their grain of truth.

Monica Hakimi says

April 17, 2018

Thanks, Dan. That all makes sense. And don't worry; I didn't really take the "realist" label as an insult. I just don't think it captures what I'm up to. I associate realism with the view that law is irrelevant to decisionmaking or a smokescreen for background policy preferences. But I'm one of the few people who's saying that, in this case, states acted like international law mattered and had independent normative force. Almost everyone else seems to think it was irrelevant.

Also, for what it's worth: I think the questions I'm asking are quintessentially legal questions. At least, they're questions that practicing lawyers (including in national legal systems) have to think about and answer all the time. I get that others define the law and the role of lawyers more narrowly. One has to ask why. The usual answer -- that law and politics must be separate enterprises so that law is not infected by politics -- does not work for the jus ad bellum. In this area, law and politics have always been, are now, and will for the foreseeable future be interconnected. Pretending that they are separate, even when they are not, does not, in my view, help preserve the law. It relegates it to oblivion.

Anyway, thanks for clarifying your point and engaging with me!


Marko Milanovic says

April 18, 2018

Hi Monica,

Just a couple of points:

(1) I don't think the divide here is between those of us who think the law is separate from politics, and those who think the two are intertwined. I at least fully agree with the latter position. It is just that law has to be DISTINCT, in some way, from politics, even if it is not entirely separate from it. There has to be something we as international lawyers do that is different from those who practice politics, a value that we add. And that value is arguing out of rules and principles of a general applicability, which are not contingent on the exceptional facts of any given case, and doing so in a particular formalized fashion. Much in the same way as a constitutional lawyer does something distinctive from domestic politics, but not entirely separate from it. One problem with these specific Syrian strikes is precisely in the failure of two of the intervening states to articulate any legal argument, with a minimum level of formality.

(2) This does not mean, however, that international law was irrelevant for these states. On the contrary - it was very relevant, and it mattered; even their silences were shaped by it. It's just that they decided to breach the law, for reasons which are understandable or not, and also decided not to try to modify the law for the future, which is why they decided (the UK aside) not to articulate a legal argument. In other words, they thought that the law was good, fit for purpose, but that this was an aberrant situation which justified a departure from it. Again, one can agree with that assessment or not (I don't), but that doesn't mean the law did not matter. That the law was breached does not mean that it was not relevant.

Monica Hakimi says

April 18, 2018

Well hello, Marko! Thanks for coming to "my" comments section :)

I agree that one of the defining features of law is that it purports to speak on behalf of a governed group, by reference to general principles.

Here's where we might disagree:

(1) For me, the principles can be generalizable (and legal), even if they are not articulated as concrete standards that control future cases. They can be varied and competing, such that they require case-specific balancing and the exercise of discretion. Here, law takes the form of a series of fact-specific decisions. Any particular decision is "legal" in part because it purports to represent the interests of the group; it is justified by reference to a mix of principles that are generalizable for the group.

(2) I think many states that conducted and supported the Syria operation made that kind of decision. They implicitly acknowledged that the decision was contrary to one legal principle (the requirement of SC authorization), but they claimed that it was justifiable in the service of others (e.g., the prohibition of chemical weapons and Charter objectives). So, I think they made legal decisions.

(3) If I understand you correctly, you're saying that law was relevant because it affected how states talked about the decisions that they made for external, moral or policy reasons. I think law did more than that. For example, I think it helped them justify and therefore legitimize the decision to use force (e.g., by reference to the prohibition on chems). It also gave them reason to go to the Security Council and build a case for the operation. For me, the way they used law suggests that they weren't just acting in breach of it. They were doing something a bit more complicated than that.