The Soleimani Strike and Self-Defence Against an Imminent Armed Attack

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The US drone strike on Qassem Soleimani, one of the most important members of the Iranian leadership, raises many complex questions of international law. This post will examine the lawfulness of the strike from the standpoint of the law on the use of force. It will first set out the parameters of the US justification for killing Soleimani, which is some variant of self-defence against an imminent armed attack. It will then look at the notion of an imminent attack, at the different ways such an attack can be repelled, and at whether, on the facts as we know them, the US strike should be regarded as lawful.

I will argue that even if one accepts a broad theory of self-defence against an attack that is yet to occur, such as that espoused by the US government itself, the strike is likely to be unlawful. It is improbable that the US would be able to meet the factual requirements that it needs to justify the strike – in particular, there are serious doubts that there even was an imminent attack, and there are serious doubts that the method the US chose to resist that supposed attack was necessary under the circumstances. If such was the case, the US breached the prohibition on the use of force in Article 2(4) of the UN Charter vis-à-vis both Iran and Iraq. Finally, the post will look at the illegality of the threats of further use of force made by President Trump against Iran, which are unlawful both as a matter of the jus ad bellum and the jus in bello.

The US justification for the strike on Soleimani

It is clear that the US is relying on self-defence to justify its strike against Soleimani. It is also clear that the US is relying on self-defence not in the context of an ongoing armed attack by Iran, but with regard to a future armed attack or attacks, which the US considers to have been imminent. Thus, the initial statement of the US Department of Defense justifying the strike said that ‘the U.S. military has taken decisive defensive action to protect U.S. personnel abroad by killing Qasem Soleimani’ and that the ‘strike was aimed at deterring future Iranian attack plans.’ Subsequent statements by President Trump, his Secretary of State and National Security Advisor repeatedly referred to planned imminent attacks by Iran against the US which necessitated the killing of Soleimani:

“Soleimani was plotting imminent and sinister attacks on American diplomats and military personnel but we caught him in the act and terminated him,” Trump told reporters at his Mar-a-Lago resort.

No further detail of these imminent attacks has been publicly disclosed. While the US is yet to submit a formal letter to the UN Security Council pursuant to Article 51 of the Charter, which might clarify the US position further, it is clear that the various statements made by US officials were not purely political or designed for domestic consumption. They are a public justification for the use of force against another state, and are perceived as such by other states, with, for example, the UK Foreign Secretary saying that in his view the right to self-defence clearly applied. Self-defence against an imminent armed attack is thus the justification that the US government chose to employ for its actions, and it is against this justification that those actions should be judged. We should not ‘ascribe to States legal views which they do not themselves formulate’ (ICJ, Nicaragua, para. 266).

Now, crucially, that justification would have to work against both Iran and Iraq, because the strike took place on Iraqi territory without the consent of the Iraqi government. Pursuant to restrictivist theories of self-defence, such an argument would be a non-starter for the simple reason that Iraq was not implicated in any imminent attacks against the US. For expansionists, this situation would be analogous to self-defence against non-state actors – using force on the territory of the state in which the attacker is located would need to be justified by the necessity of stopping the attack, e.g. pursuant to an unwilling or unable theory.

In other words, the US would need to demonstrate that it had to strike at Soleimani when and where it did, that it could not ask the Iraqi government for permission (e.g. on the basis of its collusion with Iran) and that it could not wait to strike at Soleimani elsewhere. All of these points are contingent on facts yet to be established, and from what I can see it is unlikely the US could discharge this burden. Be that as it may, the remainder of this discussion will proceed on the assumption that the US could conceivably provide such a justification. I will turn now to the issue of imminence.

Self-defence against an imminent armed attack; prevention and deterrence

Readers are of course familiar with debates, old and new, about whether Article 51 of the Charter permits self-defence against armed attacks that are yet to occur. Some authors, like Mary Ellen O’Connell writing on the blog yesterday, are of the view that the language of Article 51 is clear and that it permits self-defence only against attacks that have actually occurred. Many others disagree. The notion of imminence has served as a focal point of arguments of those states and scholars who feel that confining self-defence solely to ongoing attacks would be too restrictive, but that embracing a theory of pre-emptive self-defence against any future attacks would be far too permissive. Imminence is thus a term deployed to create a theory occupying some kind of palatable middle ground.

More restrictive conceptions of imminence have seen it as a temporal concept, i.e. an imminent armed attack is one that is about to occur. More expansive theories of imminence have focused less on questions of time and more on those of necessity and causality. Recent years have seen concerted efforts by some scholars and states to push for such expansive conceptions of imminence – consider in particular in that regard the principles articulated by Daniel Bethlehem in the AJIL, subsequently embraced verbatim in the speeches of legal advisors of several powerful states (e.g. here and here).

While these efforts to expand imminence have often been conceptually muddled, it seems clear that the US and some of its allies, like the UK, do not see imminence in temporal terms. It is more of a rhetorical device than a genuinely useful legal concept – an armed attack will be regarded as imminent if responding to the attack is necessary now, regardless of when and how exactly the attack will take place (see here for an extended discussion, and the comments section in particular; see also Akande and Lieflander here). An imminent attack is thus one where the attacker has committed to particular aggressive course of action which they will not desist from absent some kind of intervention in the causal chain, such as a use of force in self-defence.

Let us then also proceed, for the sake of the argument, on the assumption that these expansive positions are correct, i.e. that self-defence is available against imminent attacks, and that an imminent attack is not defined as one that is about to occur, but as one which necessitates immediate defensive action to successfully repel it. Logically, there are two possible forms of such action.

Two basic ways of disrupting an imminent attack

First, the state acting in self-defence could use force against those persons or objects of the attacking state that will be used to execute the attack in the future. Think, for example, of an air strike against the attacking state’s tanks about to cross the border, or against their fuel supply lines. Second, the state acting in self-defence could use force against the assets of the attacking state that are not indispensable for the execution of the planned attack, with the purpose of exacting pain or damage on the attacking state so as to deter it from pursuing the planned attack.

Therefore, the first response disrupts the attacker’s ability to pursue the attack, the latter its will to do so. The first response is more easily squared with the exceptional nature of self-defence under the Charter; the second is in tension with the idea of imminence as an irrevocable commitment of the attacker to pursue the attack, and in many cases might be difficult to distinguish from an unlawful, punitive armed reprisal (see this EJIL article by David Kretzmer for an extensive discussion).

On the facts of the Soleimani strike, the US appears to have engaged in both types of response, or at least has offered both types of justification. Thus, Secretary of State Pompeo justified the killing by saying that:

“He [Soleimani] was actively plotting in the region to take actions – a big action as he described it — that would have put dozens if not hundreds of American lives at risk. We know it was imminent,” Pompeo told CNN, echoing an earlier Pentagon statement on Thursday.

“These were threats that were located in the region,” Pompeo added. “Last night was the time that we needed to strike to make sure that this imminent attack … was disrupted.”

Pompeo’s general idea here seems to be that killing Soleimani was necessary, i.e. this was the last opportunity to strike, and doing so did in fact prevent some (unspecified) attack, because Soleimani was actively involved in its planning. However, the various other statements of US officials (including the very first DoD one) are replete with references to deterrence, i.e. an attempt to influence decision-makers in Iran to desist from a particular course of action.

While it is certainly possible that killing Soleimani did have a concrete operational impact on some planned attack by Iran, the US has offered no evidence that such was the case. And Soleimani’s high-ranking position makes such an indispensable operational role unlikely; his role was in providing strategic direction and materiel to Iranian proxies in Iraq, not in the execution of specific operations. Thus, the ‘US Army General Mark Milley, the chairman of the Joint Chiefs of Staff, told reporters that violent plots by Soleimani might still happen despite his death.’

As well explained by an analyst:

“There may well have been an ongoing plot as Pompeo claims, but Soleimani was a decision-maker, not an operational asset himself,” said Jon Bateman, who served as a senior intelligence analyst on Iran at the Defense Intelligence Agency. “Killing him would be neither necessary nor sufficient to disrupt the operational progression of an imminent plot. What it might do instead is shock Iran’s decision calculus” and deter future attack plans, Bateman said.

It might be argued that because of its enormous potential for escalation, even with the constraining influence of necessity and proportionality, the deterrence rationale should be categorically excluded from the legitimate scope of self-defence. But, even assuming its permissibility in principle, the basic problem with a deterrence rationale is that it is practically impossible to know ex ante whether a use of force for that purpose would actually work. Whereas the effectiveness of striking at assets directly involved in the planned attack is capable of at least some measure of objective assessment (e.g. destroying the tanks will in fact stop the attack), the same cannot be said, absent extraordinary circumstances, of an attempt to influence the attacking state’s ‘decision calculus.’ It in fact seems manifest that Soleimani’s killing had the exact opposite effect on Iran’s leadership, which has publicly committed to avenge him.

Obviously, it is impossible to know for sure whether Soleimani’s killing had some kind of deterrent effect without knowing anything about the specifics of the purported imminent attacks by Iran which this strike was designed to disrupt. But that is exactly my point – it seems unlikely in the extreme that the US government itself could have been able to reliably assess the extent of such a deterrent effect before it decided to kill Soleimani. Framed as deterrence, the strike just does not seem to work as intended. And if it is incapable of so working, it cannot be considered necessary for the purpose of Article 51.

To be clear, I am not saying here that any failed attempt at self-defence is ipso facto unlawful. Rather, if in the specific context the state purporting to act in self-defence has no idea whether a deterrent action will actually be able to stop an imminent attack, such an action is simply unsuitable for its stated purpose and accordingly cannot be necessary.

Was there in fact an imminent attack?

A further, logically prior problem for the US self-defence justification is that the existence of an imminent armed attack by Iran seems to be undermined by its own intelligence. According to a report in The New York Times:

But some officials voiced private skepticism about the rationale for a strike on General Suleimani, who was responsible for the deaths of hundreds of American troops over the years. According to one United States official, the new intelligence indicated “a normal Monday in the Middle East” — Dec. 30 — and General Suleimani’s travels amounted to “business as usual.”

That official described the intelligence as thin and said that General Suleimani’s attack was not imminent because of communications the United States had between Iran’s supreme leader, Ayatollah Ali Khamenei, and General Suleimani showing that the ayatollah had not yet approved any plans by the general for an attack. The ayatollah, according to the communications, had asked General Suleimani to come to Tehran for further discussions at least a week before his death.

Assuming that this report is factually correct, it seems difficult to qualify the supposed planned Iranian attack as imminent, for the simple reason that the person who had to decide on whether the attack will take place – Ayatollah Khamenei – was yet to make his decision. In other words, even if imminence was no longer a temporal concept but a purely causal one, as the US and other expansive theories of imminence argue, the planned attack was not imminent because Iran was yet to commit to that particular course of action.

Bottom line on the Soleimani strike

In conclusion, even if we took the US views of applicable international law on their own terms, fully accepting that self-defence pursuant to Article 51 of the Charter extends to imminent armed attacks, embracing an expansive, non-temporal conception of imminence, and accepting a wider scope of permissible goals in self-defence, it would be difficult to argue that the killing of Soleimani was lawful under the jus ad bellum (I leave aside here the issue of the legality of his killing under international humanitarian law (if it applied) or international human rights law). The US self-defence justification is factually contingent on a number of points.

It is only if the US could establish that (1) Soleimani was operationally involved in the planning of future attacks against US assets and personnel; (2) that Iran was committed to pursuing these attacks, i.e. that it was virtually certain that they would take place because a final decision had been made in that regard; (3) that killing Soleimani would in fact have disrupted those attacks; (4) that killing him was the only way of disrupting those attacks, i.e. that no options short of the use of force would have succeeded in disrupting the attacks; (5) that killing him in Iraq, at the time the strike took place, was necessary to disrupt those attacks – it is only then that the strike against Soleimani could arguably be lawful, even under broader theories of self-defence that the US government espouses. This would require a much more detailed disclosure of the relevant evidence and facts than are currently available.

It is in my view unlikely that the US could discharge this burden, but it is not inconceivable that it could do so. The Soleimani strike is thus not clearly unlawful in the way some previous military actions of the Trump administration have been (here and here). But it is imminently unlawful. The lack of any specific details provided publicly and the disclosure of US intelligence that goes against US interests cast serious doubts on whether the various factual predicates for lawful self-defence could be met even on a generous appraisal of the facts. Similarly, the deterrence rationale for killing Soleimani, even if admissible in principle, collapses under the weight of its own failure, a failure that was easily foreseeable.

Clearly unlawful threats to use force

This brings us, finally, to the one clear and unambiguous violation of Article 2(4) of the Charter – Trump’s threats by tweet against Iran after Soleimani’s killing, warning that in case Iran responds the US has:

Trump of course has some form in the crassness of his threats. And, faced with the criticism of his reference to attacking Iranian cultural sites – which would be a violation of IHL and potentially even a war crime – he characteristically doubled down:

Speaking to reporters aboard Air Force One a day later, he sought to offer a justification. “They’re allowed to kill our people,” Trump said, according to a pool report. “They’re allowed to torture and maim our people. They’re allowed to use roadside bombs and blow up our people. And we’re not allowed to touch their cultural site? It doesn’t work that way.”

I am afraid that it precisely does work that way (not that Iran is actually ‘allowed’ to do any of those things). One war crime does not justify another. Even putting aside the cultural site issue, Trump’s reference to 52 targets chosen to symbolize 52 American hostages taken in Tehran almost 40 years ago (all of whom ultimately lived to tell the tale), demonstrates the purely punitive intent behind his words. So does his reference, in yet another tweet, to a potentially ‘disproportionate’ (his word) US response. This is a very specific threat, especially when taken in its context; it cannot be dismissed as simple rhetoric. And not only is such language shameful coming from a President of the United States, but it lays bare the total arbitrariness behind the proposed use of force, which cannot be reconciled with any legitimate conception of self-defence in international law.

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Dave Winsar says

January 7, 2020

There are other emerging perspectives on this assassination worth considering and understanding:

Matthias Zechariah says

January 7, 2020

Prof Milanovic, this is a very brilliant and insightful article. The depth of your analysis is, indeed, professorial. However, I have observed that there is a gap in your approach to the issues that needs addressing; or rather, you should have given at least a cursory attention to events predating or building up to the assassination of the Iranian General Qassem Soleimani. The USA had advanced another argument, which one of the quotations you have cited above mentioned: thus,Qassem was implicated him in the killings of many Americans in the course of Iran's military operations in the Middle East sub-region. From US position, it would appear that the influential General was a strategist that had utilized or committed his youthful years, ideas,skills and life to fighting Americans and American interests/targets in the Middle East.What is your take sir?
Prof should have advanced that argument to determine whether it falls/fell within the paradigms of lawful or unlawful use of force ad bellum and/or in bello; or whether it merely took a life of its own, as it were. A key concept that might arise in such a discourse is 'reprisal' or 'vengeance'. Interestingly,or even as a matter of concern, Iran is threatening 'harsh vengeance' on America; hence, this is a burning issue. Personally, I am curious to read a professorial view on that perspective. Thank you. Matthias Zechariah, Lecturer in Public International Law.

Mary Ellen O'Connell says

January 7, 2020

Dear Marko,

Thank you for linking to my post of yesterday. I do need to point out that I am always careful to use the actual terms of the Charter. Article 51 says "if an armed attack occurs", not the words you attribute to me: "Some authors, like Mary Ellen O’Connell writing on the blog yesterday, are of the view that the language of Article 51 is clear and that it permits self-defence only against attacks that have actually occurred."

I say more in the post on why those actual terms are critical, not only for compliance with the Charter but for meeting the full requirements of the jus ad bellum, including the principles of necessity, and proportionality. You have added further analysis of the problems the U.S. has in making a convincing case for self-defense in the killing of Soleimani.

When force in self-defense is prohibited, states have alternative responses to threats of violence. We in international law can contribute for more scholarship on these alternatives. I cannot think of a more important time to do so.


Mary Ellen

Christian Tyller Campbell says

January 7, 2020

The killing, its consequences and legality are very concerning. Prof Milanovic lays out many of the traditional legal considerations very clearly, but I wonder how useful it all is in the context of "fourth generation warfare". It seems General Soleimani was a fourth generation warrior.

Marko Milanovic says

January 7, 2020

Dear Matthias,

Thanks for your comment. My analysis in the piece is confined solely to the jus ad bellum. To the extent IHL/jus in bello applied to S's killing, which is a complicated question (e.g. due to a possible preexisting international armed conflict), S would be a lawful military target as he was a combatant. But that does not obviate the need for an ad bellum analysis. As for human rights law, the basic idea there would be similar to the self-defence analysis, but with stricter criteria and likely a temporal conception of imminence. I.e. the US could kill S only if it could demonstrate that he posed an immediate threat to the lives of other and that using lethal force was the only way of neutralizing that threat. The whole deterrence rationale would have no place there.

Dear Mary Ellen,

Thanks for this. Apologies if I misconstrued your position, I was (am!) writing this in the throes of a very bad flu, but what I meant to say is what you said, i.e. that you believe that self-defence is only possible if an armed attack occurs, as the Charter says, and that there is no possibility of self-defence for future attacks, imminent or not

Kishor Dere says

January 7, 2020

One has to wait and watch what sort of evidence does the US provide to justify its action. Moreover, it is also to be seen what Iran would do to disprove the US position. It is indeed difficult to decipher what goes on in the minds of decision-makers. One does not know whether they can be rightly equated with black boxes. There is always a cognitive gap between and among policy-makers. Subjectivity and even eccentricity overshadow objectivity. Above all, national security cannot be compromised by any of the nations. Thus, it is a case of zero-sum game, struggle for survival and domination, along with balance of power in the anarchic world order. Dr Marko Milanovic has done an excellent job by raising a number of pertinent issues involving international law. One can hope (against hope!) that international law would guide the decision-makers in matters of national security.

Marty Lederman says

January 7, 2020

This is, not surprisingly, great, Marko--much more careful and nuanced than anything else I've seen. As you note, the key questions are whether this particular response to the threat was necessary and whether it could reasonably be thought that it would more likely diminish, rather than exacerbate, the threats to U.S. forces/nationals/facilities. And all of that depends on the underlying intel, which probably won't be forthcoming any time soon.

A couple of recent things to consider:

Lowly Visitor says

January 8, 2020

Mr Lederman's post above has a key link which seems to have been missed/ignored in Mr and Ms O'Connell's posts/comments. I mean, this quibbling over "imminent" - Iran and it's proxies have been doing this for years, including rockets into a US base days before the Embassy "protests". Is Dec 27 too long ago? Anyway, lots of details here via Reuters quoting "two militia commanders and two security sources briefed on the gathering".
The strategy session, which has not been previously reported, came as mass protests against Iran’s growing influence in Iraq were gaining momentum, putting the Islamic Republic in an unwelcome spotlight. Soleimani’s plans to attack U.S. forces aimed to provoke a military response that would redirect that rising anger toward the United States, according to the sources briefed on the gathering, Iraqi Shi’ite politicians and government officials close to Iraqi Prime Minister Adel Abdul Mahdi.

Interviews with the Iraqi security sources and Shi'ite militia commanders offer a rare glimpse of how Soleimani operated in Iraq, which he once told a Reuters reporter he knew like the back of his hand.

Two weeks before the October meeting, Soleimani ordered Iranian Revolutionary Guards to move more sophisticated weapons - such as Katyusha rockets and shoulder-fired missiles that could bring down helicopters - to Iraq through two border crossings, the militia commanders and Iraqi security sources told Reuters.

At the Baghdad villa, Soleimani told the assembled commanders to form a new militia group of low-profile paramilitaries - unknown to the United States - who could carry out rocket attacks on Americans housed at Iraqi military bases. He ordered Kataib Hezbollah - a force founded by Muhandis and trained in Iran - to direct the new plan, said the militia sources briefed on the meetings.

Soleimani told them such a group “would be difficult to detect by the Americans,” one of the militia sources told Reuters."

Seriously, what more do you need? Planning these "What,!?" asymmetrical attacks was literally Soleimani's job! And all you naive western ICJ professors take the bait. As in: "Wait until he bombs us first! Then figure out why we deserved it -- the poor guy was just acting out against imperialism!"

All of these posts seem very intentionally nuanced to accommodate prior biases (e.g. the orange man is bad). I am sorry to say, but "nicely punctuated but special pleading".

Lowly Visitor says

January 8, 2020

Typo, meant to be "Mr Milanovic and Ms O’Connell’s posts/comments".

Marko Milanovic says

January 8, 2020

Thanks a lot for the comment Marty. The Reuters article is very interesting. If what it reports is true, however, it does not seem to advance the Trump administration's imminence rationale. The meeting it reports on took place IN OCTOBER, and the various attacks on US interests that Soleimani had initiated have already been taking place. And it seems clear from the report that his role was a strategic one, i.e. that he provided Iranian proxies with weapons and direction, but was likely not involved in specific operations. That goes to the point in my piece about how killing him would not actually stop any planned attack (paradoxically, killing the head of Kataib Hezbollah might have had such an effect).

James Rowles says

January 8, 2020

"Lowly Visitor" cites an article by Reuters based on writing by Michael Georgy and editing by Brian Thevenot. It contains what sound like extraordinary intelligence revelations, but is very thinly sourced, and must be regarded with considerable doubt as to the authenticity of the information reported.

Marty Lederman says

January 8, 2020

Hmmm, perhaps I misread you, Marko. If the Reuters account, and the account of the DOD officials, is true (a big "if," to be sure), it might not mean that that killing Soleimani would interdict any particular, already planned, attack. I had thought you agreed with me and with Dapo, however--at least in the comments to the 2017 post--that there's no requirement that the action in self-defense must interdict a *particular* attack. If those accounts are true (once again, a big "if"), they indicate that the U.S. believed Soleimani was responsible for planning an ongoing *series* of attacks, as part of an effort to ratchet up pressure on the U.S. and change the dynamic in the region. The fact that some of the attacks already had occurred, or were in the final stages of planning, would, on this view, help to demonstrate that he and his forces not only had the capability of striking in the future, but also the will, the plan to do so, and the wherewithal--that they were, in effect, committed to an *ongoing campaign* of strikes against U.S. forces, at his direction and control. In which case, killing him would be likely to at least diminish the frequency and effectiveness of future attacks. As you rightly and importantly insist, that in and of itself wouldn't satisfy the necessity requirement (and possibly not proportionality, either)--for that, Trump would have needed more evidence concerning the relative ineffectiveness of less belligerent alternatives, and reason to believe that killing Soleimani wouldn't make things *worse* in the long run. But the fact that the U.S. didn't know of any *particular* attack that was merely in the early, planning stages--but instead knew "merely" that Soleimani was committed to continuing to coordinate and direct such attacks--shouldn't in and of itself undermine the S-D rationale. To the contrary. It'd be equivalent to targeting the very effective strategic commander of State B in an "active" state-to-state armed conflict: Even if State A doesn't know exactly what he or she has in mind for the next few weeks or months, there's good reason to believe that officer will continue to do what he or she has already been doing, absent some reason to think the campaign of attacks has reached its conclusion. Yamamoto; bin Laden; etc. Or so Dapo & Thomas, and I, have argued. Do you disagree?

Marty Lederman says

January 8, 2020

In an abundance of caution, I should add that I'm confident we agree about this much--something worth stressing in all of our legal analyses: Even if the strike somehow could have satisfied the requirements of proportionality and necessity, that wouldn't mean that it was wise to order it. Indeed, from all we can tell just now, it might well have been a uniquely disastrous decision, especially from the U.S.'s own perspective, even if it didn't breach the Charter. Legality vel non is the least of it.

(Oh, and by the way, even if it *might* have been lawful under the Charter for the U.S. to engage in the strike, that wouldn't mean, for domestic constitutional purposes, that Trump could order it without congressional authorization--a further question that would require similar, but additional, analysis in order to answer confidently.)

Aditya Roy says

January 8, 2020

Dear Marko,
A very informative and exhaustive article on the Soleimani assassination. However, I was thinking if the Security Council or General Assembly could ask ICJ for an advisory opinion with regard to the permissible extent of self-defence under Article 51 of the UN Charter.The important issues such as whether the use of the word inherent talks about pre-emptive or anticipatory self defence given the nature of Conflict has changed since the Charter came. This will also put rest to the speculation with regard to the contours of self-defence against Use of Force.
Thanking You
Aditya Roy

Marko Milanovic says

January 8, 2020

Hi Marty,

Agree entirely on the 'lawful but awful' point. Legality (vel non) here is only one aspect of the picture, obviously.

Re the Reuters report I agree that it could plausibly be read as you suggest. At least under those expansive theories of imminence, the victim state doesn't need to know the precise details of the future attack (but it has to know something about it other than just there being a vague threat). So that report could be read as supporting a theory of an ongoing series of attacks by Iran, which is in progress.

The problem with that view is that this is not what US officials have actually said - all of those statements seemed to refer to something more specific and not an ongoing series. (A 'big action' etc). Plus there's that reference in the NYT article I quoted in the post about some specific attack yet to be decided on by Khamenei.

Finally, there is as you say the necessity point, which I also addressed in my last comment. If S had set a series of attack in motion there seems to be no evidence that killing S would stop what remains of that series.

Hi Aditya,

It is exceptionally unlikely that the SC or GA would actually request such an AO from the Court. There are far too many conflicting interests for that to happen. Plus many states like the existing ambiguity about some aspects of the jus ad bellum.

Liron A. Libman says

January 8, 2020

Dear Marko,
Thanks for a very detailed and nuanced analysis.
I am just wondering about the departure point of the analysis. You wrote "It is also clear that the US is relying on self-defence not in the context of an ongoing armed attack by Iran, but with regard to a future armed attack or attacks".
Is it indeed the case? You have graciously provided a link to the DoD initial statement in which more words are dedicated to describing past attacks attributed to Iran and Soleimani than to the future ones anticipated. It seems to me that the position of the US is that an armed attack by Iran on the US has occurred and that the threat of future attacks is brought to support necessity, since an armed attack that was clearly over does not necessitate self defence – as you noticed on your piece about the Iranian recent missile attack.
I wonder if you agree there should be a heavier burden of proof when a state is the first to use force, claiming anticipatory or preemptive self-defence against future attacks, as opposed to when an armed attack has occurred and a state respond claiming that future attacks are expected?
States may have political, even domestic reasons not to use the words "war" or "armed conflict" to describe their current relations. However, if is it clear that an armed conflict exist between Iran and the US after the Iranian last missile attack (as you argue in your last piece) and you assume the US claims of previous Iranian attacks true, why wasn’t there an armed conflict before the killing of Soleimani?

Marty Lederman says

January 8, 2020

"The problem with that view is that this is not what US officials have actually said – all of those statements seemed to refer to something more specific and not an ongoing series."

It appears, of course, as though they're constructing a legal defense as they go (indeed, after they went). That said, I think they're now coalescing around a narrative that emphasizes *both* the recent attacks (such that killing Soleimani was not "purely" an anticipatory "first use"--the completed attacks demonstrate resolve, plan, capability, etc.) *and* the planned future ones, which are the things to be defended against. The completed attacks, in other words, could demonstrate that the threat posed by the future plans are very real, not speculative (which is of course very relevant, albeit not sufficient, in assessing necessity). I discuss all of this in greater detail--and why we should all stop referring to "imminent attacks"!--here:

Marko Milanovic says

January 8, 2020

Dear Liron, thanks for that - I think your point very much goes to the discussion that Marty and I had in the last few comments. Let's see how the US position evolves.

Matthias Zechariah says

January 8, 2020

I am extremely grateful to Prof Milanovic for responding to my question. I am better informed now. I am feeling like a Professor too!
International law will never run dry of topical subjects: Just when I was waiting for Prof's response on the issue of reprisals or "harsh vengeance", Iran struck at designated US military bases in Iraq last night. That action reminded me of a topic I had discussed with my undergraduate law students on non-pacific methods of settlement of international disputes. The latest attacks by Iran raises legal issues on use of force that I believe EJIL: Talk! will discuss in the coming days. In fact, I have already cited an EJIL: Talk! post on it; though I am yet to read it.
I would like to use this platform to thank the editors and management of EJIL and of the EJIL: Talk! in particular, for their tremendous contributions to scholarship. My students and I have benefited from the rich resources posted on this platform by the editors and by many other contributors. I am also pleased to read from Prof Mary O'Connell, another reputable international law scholar, whose works I have read and cited in some of my write-ups. Keep up the good work. Matthias.

Anne Lagerwall says

January 24, 2020

Dear Marko,

Now that we have had the time to read the letter sent by the US to the Security Council, it appears that the preventive character of the attack of 3 January is not the main argument or the only argument, as the US rather argued that the attack was "in response to an escalating series of armed attacks in recent months by the Republic Islamic of Iran and Iran-supported militias on U.S. forces". Do you believe that this argument is convincing ?

I don't think it is, for reasons (insufficient evidence, lack of gravity and uncertain attribution to Iran) developed with Olivier Corten, Vaios Koutroulis and François Dubuisson in a text available here in pdf :

Javed Jiskani Baloch says

February 14, 2020

It is always hard to apply the laws of war in proxy settings of cold war or hybrid war frameworks of conflicts like the one going on between Iran and the USA because everything is shrouded with mysteries, classifications and secrecies unless a proper investigation/research is made into the matter.

Panayiotis Constantinides says

February 14, 2020

Dear Professor Milanovic,

Thank you for your informative insight into the jus ad bellum implications of the Soleimani targeted killing. I would be grateful if you could share your views on how to reconcile the reaction of the United Kingdom qualifying the attempted assassination of Sergei Skripal and his daughter as a 'use of force' in violation of Article 2(4) UN Charter (but falling short of a use of force that could trigger self-defence) with Iran's qualification of Soleimani's targeted killing as an assassination giving rise to self-defence under Article 51 UN Charter.

Can the reactions of both States be considered as state practice indicating a shift towards the abandonment of the view that there exists a de minimis threshold within Article 2(4) ? By implication, can we argue that targeted killings of individuals are increasingly considered as violating the prohibition of the use of force within Article 2(4)? More fundamentally, do these case studies indicate that States are increasingly stretching jus ad bellum language to give effect to their foreign policies?

Thank you in advance.

Panayiotis Constantinides (Advanced LL.M. in Public International Law at Leiden University)