The Killing of Soleimani and International Law

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On 3 January, missiles launched from a United States Reaper drone struck two vehicles leaving Baghdad’s international airport. At least seven people died in the attack, including the commander of Iran’s Quds force, General Qassem Soleimani. On 5 January, Iranian Major General Hossein Dehghan, reported to be the military adviser to Iran’s Supreme Leader, gave an exclusive interview to CNN and said Iran “would retaliate directly against US ‘military sites.’”

These killings and threats are the focus of this brief post. Developments are on-going, but enough has occurred so far to be able to analyze relevant principles of the jus ad bellum.

The killings and response have received extensive press coverage, unlike most drone attacks, such as the 63 against Somalia in 2019 alone. In connection with Soleimani, reporters have actually been asking about the legality of the killing. See Was It Legal to Kill a Top Iranian Military Leader? Much of the attention has focused on whether it was an “assassination”. In a call to reporters a U.S. State Department official rejected the term “assassination” to characterize the killings because ‘“Assassinations are not allowed under law.’” The answer leads to the next question, were the killings lawful?

The official went on to provide the analysis U.S. presidents have apparently relied on to justify killing with drones since 2002. (See, Mary Ellen O’Connell, Game of Drones Game of Drones, Review Essay, 109 Am. J. Int’l L. 889 (2015).) He applied two criteria to the case: “‘Do you have overwhelming evidence that somebody is going to launch a military or terrorist attack against you? Check that box. The second one is: Do you have some legal means to, like, have this guy arrested by the Belgian authorities or something? Check that box, because there’s no way anybody was going to stop Qassem Soleimani in the places he was running around—Damascus, Beirut. And so you take lethal action against him.’”

President Trump has also provided many tweets and other remarks relevant to a legal assessment. He said he ordered the attack to “prevent a war”, not as part of an on-going armed conflict with Iran. He also used terms relevant to a case for self-defense under the jus ad bellum. Suleimani, according to Trump, ‘“was plotting imminent and sinister attacks on American diplomats and military personnel, but we caught him in the act and terminated him.”’

The U.S. Department of Defense in a brief press statement also inferred self-defense. The U.S. took “decisive defensive action to protect U.S. personnel abroad… General Soleimani was actively developing plans to attack American diplomats and service members in Iraq and throughout the region.” 

Outside of an on-going armed conflict, the first use of military force is regulated under the jus ad bellum. The first principle of the jus ad bellum is the prohibition on the use of force, a peremptory norm codified in United Nations Charter Article 2(4). The only possible exception to the prohibition applicable in this case is self-defense. The exception is narrow. Some restrictions are provided in UN Charter Article 51; others in the general principles of international law. Article 51 permits the use of military force in such as the Hellfire missiles carried by Reaper drones, if “an armed attack occurs”. The International Court of Justice has emphasized that the attack must be “grave”.  The ICJ has made this point in more than one case, but given the current protagonists, it is appropriate to cite from the case Iran brought against the U.S. for uses of military force against Iranian property that resulted in deaths.

The ICJ said in the Oil Platforms case:

…[I]n order to establish that it was legally justified in attacking the Iranian platforms in exercise of the right of individual self-defence, the United States has to show that attacks had been made upon it for which Iran was responsible; and that those attacks were of such a nature as to be qualified as “armed attacks” within the meaning of that expression in Article 51 of the United Nations Charter, and as understood in customary law on the use of force. As the Court observed in the case concerning Military and Paramilitary Activities in and against Nicaragua, it is necessary to distinguish “the most grave forms of the use of force (those constituting an armed attack) from other less grave forms” (I.C.J. Reports 1986, p. 101, para. 191), since “In the case of individual self-defence, the exercise of this right is subject to the State concerned having been the victim of an armed attack” (ibid., p. 103, para. 195).

Oil Platforms (Iran v. United States), Merits, Judgment of 6 November 2003, ICJ Reports 2003, para 51.

In addition to the significant armed attack, the general principle of necessity requires that the defensive military response be a last resort and one that is likely to succeed in accomplishing the lawful objective of defense. The use of force must not be disproportionate to the injury suffered by the victim state, and it must aim at the state legally responsible for the attack. If the attack is over with no follow-on attacks occurring, it is unlikely that the requirement of necessity can be met. Such intermittent attacks require alternative responses to the use of military force, such as countermeasures.

In Legality of the Threat or Use of Nuclear Weapons (Nuclear Weapons), the ICJ found ‘a “specific rule whereby self-defense would warrant only measures which are proportional to the armed attack and necessary to respond to it, a rule well established in customary international law.” This dual condition applies equally to Article 51 of the Charter, whatever the means of force employed.’ ICJ, Legality of the Threat or Use of Nuclear Weapons (Nuclear Weapons), Advisory Opinion of 8 July 1996, ICJ Reports 1996, 245, para. 41 (quoting ICJ Reports 1986 at 94, para. 176).

The Court applied these principles in Oil Platforms to find both that the US had submitted insufficient evidence to prove Iran had carried out attacks on its ships. Even if attribution had been proven, however, the court doubted the necessity of the US counter-attacks:

‘[T]he Court is not satisfied that the attacks on the platforms were necessary to respond to these incidents. …[T]here is no evidence that the United States complained to Iran of the military activities of the platforms, in the same way as it complained repeatedly of minelaying and attacks on neutral shipping, which does not suggest that the targeting of the platforms was seen as a necessary act. …[I]n the case of the attack of 19 October 1987, the United States forces attacked the R-4 platform as a “target of opportunity”, not one previously identified as an appropriate military target …’

The facts of the Soleimani killing do not meet these elements of lawful self-defense. The attacks that have already occurred raise questions of attribution as well as gravity, necessity, and proportionality. More importantly, the law does not permit the use of military force to respond to an alleged plan to attack in the future. U.S. officials stress that attacks were “imminent”. The New York Times, however, has cast doubt on intelligence reports do not support the claim that attacks were “imminent”. The idea that a right of self-defense is triggered by an “imminent” attack was first introduced by Derek Bowett in the wake of the Suez Crisis as a justification for the British use of force. “Imminence” does not appear in Article 51. The actual words are “if an armed attack occurs.”

Necessity and proportionality cannot be assessed with respect to attacks that are not yet occurring. Claims for a right to pre-empt future attacks do not meet the jus ad bellum requirements for lawful resort to force. See Mary Ellen O’Connell, The Art of Law in the International Community (Cambridge University Press, 2019), chapters 2 and 4. Moreover, it is inconsistent with self-defense to single out one military commander. The right is for a state to defend itself from another state.

Note that these principles apply equally to Iran. The killing of Soleimani can be attributed to the U.S. but was it grave enough to permit military force in response? Moreover, any military response now will not be aimed at halting and repelling attacks.

Without a justification under the jus ad bellum, the relevant law that remains is peacetime human rights. This law is clear that if the United States has intelligence that Soleimani was plotting attacks on U.S. personnel in Iraq, the appropriate response was to take the information to Iraqi authorities. It was the duty of the Iraqis to keep the invited Americans safe from the criminal acts of others on their territory. Iraq is bound by human rights law in dealing with criminal conduct of the type linked to Soleimani. In a case with certain parallels, the European Court of Human Rights set out the standard: Authorities may exercise lethal force only when “absolutely necessary in the defence of persons from unlawful violence.” McCann & Others v United Kingdom, Eur. Ct. H.R., Judgment of Sept. 27, 1995, ¶148. Similarly, the United Nations Basic Principles for the Use of Force and Firearms by Law Enforcement Officials (“UN Basic Principles”).

In the event the Iraqis failed to take adequate steps, the U.S. can keep its people safe by evacuating them from Iraq. Ironically, that is what the U.S. is busy doing now as the danger to Americans has grown exponentially following the killing of Soleimani. The Iraqi Parliament has voted for U.S. forces to leave in the wake of the violation of their sovereignty. The unlawful use of force has not aided the U.S. It will set back Iran even further from its urgent goal of economic prosperity.

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Koorosh Ameli says

January 6, 2020

Well done, especially because the rule equally applies to both sides.

Patrick S. O'Donnell says

January 6, 2020

Perhaps I misunderstand it, but is the sentence, "The facts of the Soleimani killing do meet these elements of lawful self-defense," missing the word "not" between "do" and "meet" here?

Thank you.

Nicolas Boeglin says

January 7, 2020

Dear Professor O´Connell

Many thanks for this extremely useful analysis and the valuable information provided.

Checking carefully the US Department of Defense press release that you quoted, it can be read that: "At the direction of the President, the U.S. military has taken decisive defensive action to protect U.S. personnel abroad by killing Qasem Soleimani".

In your view, is it very common to find the expression " At the direction of the President" in this kind of text issued by US Department of Defense? If not, could we interpret it as a way to indicate that this particular military option didn´t have the approval of the Department of Defense?

Sincerely yours

Nicolas Boeglin

Jacob Hansen says

January 7, 2020

"The idea that a right of self-defense is triggered by an “imminent” attack was first introduced by Derek Bowett in the wake of the Suez Crisis as a justification for the British use of force. “Imminence” does not appear in Article 51. The actual words are “if an armed attack occurs.” Necessity and proportionality cannot be assessed with respect to attacks that are not yet occurring. Claims for a right to pre-empt future attacks do not meet the jus ad bellum requirements for lawful resort to force."

What about the customary law regarding anticipatory self-defence which states that it is permissible to conduct a first strike when the threat of an armed attack is 'imminent'. The Charter codifies the pre-existing customary rule of self-defence but does not exhaust it.

As far as I remember the term was first formulated by Daniel Webster as he litigated the Caroline affair. The necessity for preemptive self-defense must be "instant, overwhelming, and leaving no choice of means, and no moment for deliberation." (necessity). And it must be proportionate to the imminent threat (proportionality).

The 'Caroline-test' applies in cases where Article 51 is not a permissive rule because a defensive action was taken before an armed attack occurred.

In my view the legality of the action with regards to the U.S-Iran situation stands or falls with how 'imminent' the threat actually was.

In regards to the U.S-Iraq situation I completely agree that the lawful and appropriate response would be to take the information to Iraqi authorities. However if the imminence of an attack makes such a point moot one must resort to the 'Caroline-test'.

Obviously we haven't been given all the facts yet. But if the attack(s) were indeed as 'imminent' as claimed it stands to fact that the strike could pass the 'Caroline-test'.

(English is not my first language so I apologize for grammatical errors).

Aditya Roy says

January 7, 2020

Dear Professor,
Many Congratulations on a thorough analysis of the situation.However, Isn't this a case of Targeted Killing because all the elements are satisfied such as first, employing lethal force against human beings. Second, it involves the intent, premeditation, and deliberation to kill.
Third, the requirement of targeting individually selected persons.
Fourth, At the time of their killing, the targeted persons are not in the physical custody of those targeting them.
Kind Regards
Aditya Roy

Danbala Garba says

January 7, 2020

Thank you Prof.

This is a well articulate analysis of the Soleimani case. It's definitely going to expand scholarship in International Law.

DB Garba

Anni Pues says

January 7, 2020

Dear Mary Ellen, thank you for your comprehensive post. A single but crucial ‘not’ is missing in the first sentence after the ICJ quote. Surely it should read ‘the facts do not meet the criteria for lawful self defence’.

DeQuincey says

January 7, 2020

Prof O'Connell would you be able to respond to the points made by Craig Murray about the legality of this assassination?

He contends that the US is relying on the Bethlehem Doctrine of Pre-Emptive Self Defence, a rather more extreme version of the Caroline defence.

"Remember, this is not just academic argument, the Bethlehem Doctrine is the formal policy position on assassination of Israel, the US and UK governments. So that is lie one. When Pompeo says Soleimani was planning “imminent” attacks, he is using the Bethlehem definition under which “imminent” is a “concept” which means neither “soon” nor “definitely going to happen”. To twist a word that far from its normal English usage is to lie. To do so to justify killing people is obscene. That is why, if I finish up in the bottom-most pit of hell, the worst thing about the experience will be the company of Daniel Bethlehem."

Kishor Dere says

January 7, 2020

Jurists and experts may continue to analyze such tragic events. Unfortunately, international law, however, is subordinated, relegated, ignored and trampled upon by nations fiercely and zealously protecting their respective national interests. Therefore, for practitioners of statecraft, such decisions become regrettable but inevitable. Professor Mary Ellen O'Connell has provided a good analysis of these issues with help of case law and pointed out a clear cut distinction between the dilemmas of decision-makers, and objectivity of judicial minds attempting to judiciously adjudicate upon such delicate and sensitive matters. Let us hope that such judiciousness becomes second nature to the decision-makers.

James Rowles says

January 7, 2020

Comment by James P. Rowles*
*S.J.D. in International Law, and former Lecturer on Law, Harvard Law School

Professor Mary Ellen O'Connell's post on "The Killing of Soleimani and International Law" (EJILTalk, January 6, 2020) provides a masterful rebuttal of U.S. arguments that the targeted killing of Qasem Soleimani in Baghdad on January 3, 2020 was justified as self-defense under international law. Adding to her analysis, the following framework and clarifications may be useful in future discussions with defenders of the drone strike, including non-specialists. Four points are salient.

First, Professor O'Connell powerfully rebuts arguments that the targeted execution of Soleimani meets the self-defense requirements contained in Article 51 of the U.N. Charter. Consequently--it may be stressed to non-specialists--the attack constituted a violation of the Article 2(4) prohibition of the threat or use of force against “the territorial integrity or political independence” of any state, and therefore a violation of Iraq's sovereignty.

Second, Professor O'Çonnell dismisses a potential argument the U.S. may make (if it hasn’t already) that the attack was justified under International Humanitarian Law as taking place in the context of an "international armed conflict" between the U.S. and Iran. She does this by concluding, rightly, that the legality of the attack must be assessed under the law of the Charter and general principles of international law (which she refers to as jus ad bellum). It would strain credulity if the U.S. were to argue that it was engaged in an “international armed conflict” with Iran prior to the targeted execution of Soleimani on January 2-3, 2020.

Third, in the absence of a valid self-defense justification under Article 51 of the Charter, Professor O'Çonnell stresses that Human Rights Law still applies. The Iraqi government had a duty to protect American soldiers and diplomats in Iraq, and if they were unable to do so the U.S. had alternatives available such as withdrawing its forces from Iraq. It could not simply kill Soleimani except in compliance with international human rights law and the criminal law of Iraq, which prohibit the killing of an individual except in self-defense.

Fourth, there is a related issue which also takes us back to the issue of self-defense. Because the U.S. was acting within the territory of Iraq in carrying out the drone strike, the question arises as to whether it was doing so with the effective consent of the government of Iraq. Effective consent means prior consent. If it was, absent a valid justification of self-defense under Iraqi and human rights law, its actions would appear to amount to actions of the Iraqi government, constituting a flagrant violation of human rights and Iraqi law by both the U.S.and Iraq.

The answer to the question of Iraqi consent depends in part on whether the U.S. attack could be considered to be authorized by the “status of forces agreement” (or its equivalent) between the U.S. and Iraq, which grants permission for the presence of U.S. forces in the country. It is extremely unlikely that the terms of such an agreement contemplate the carrying out of targeted executions.

Nonetheless, a limited self-defense exception may exist in a standard clause of such agreements that allows U.S. troops to act to defend themselves. The U.S. may seek to make an argument based on such a standard clause, but it is not likely to be persuasive if stated in the kinds of broad general terms, lacking evidence and specificity, in which it has been made to date. Absent such a valid self-defense-of-forces-in-Iraq argument, which would have to meet requirements of necessity, immediacy, and proportionality—and evidence to support these requirements--the military strike that killed Soleimani would appear to constitute a violation of Article 2(4) of the Charter and of Iraq’s sovereignty.

In other words, if the targeted execution cannot be justified as self-defense of American troops in Iraq under the terms of the status-of-forces agreement or its equivalent, Iraq cannot be deemed to have given its consent through that agreement to the drone strike that killed Qasem Soleimani. Absent a valid self-defense justification based on the status-of-forces agreement, or any other express prior consent, the American drone strike would appear to be a violation of Article 2(4) and of Iraq’s sovereignty, and because the target was a high official of Iran, potentially a violation of Article 2(4) vis-à-vis Iran and of the sovereignty of Iran.

Andrea Mensi says

January 7, 2020

Dear professor O'Connell,

Many thanks for the inspiring analysis. I agree with your point of view and I find your argumentation really clear. What I found most interesting is the last part of your contribution and, particularly, what you wrote about the United States duty to co-operate with the Iraqi government.

If I may humbly add something to the debate, I believe that international lawyers should not forget "the lowest common denominators of the law". We are intuitively thinking about the killing of Soleimani in the Hohfeldian terms of "right": had the United States the right to kill Qassem Soleimani? Had the United States the right to self-defense? I think such questions are important and correct. However, as you correctly did, it is necessary to assess the legitimacy of an action also in the terms of preliminary State's duties.

Had the United States the duty to seek a co-operation with the Iraqi authorities? From my perspective, the answer is affirmative and in such situation co-operation is much more than a "empty shell" and is maybe one of the most crucial aspect of the issue and I really appreciate that you considered it in this post.

Many thanks,
Andrea Mensi

Afife Gholami says

March 1, 2020

Thank You. It was very useful and great. I wish only the issue of naming this armed action would be dealt with more, Because the phrase killing does not provide a specific legal burden, it is too neutral.