What was the International Legal Basis for the Strike on al-Zawahiri?

(Published in Just Security, Aug. 9, 2022)

The killing of al-Qaeda leader Ayman al-Zawahiri in a CIA drone strike has been touted as a political win for President Joe Biden, a vindication for an over-the-horizon counter-terrorism strategy, and even as “justice served.” Yet there appears to be little interest in whether it was lawful. The media has not seriously raised the question, the punditry has not addressed it, and the government has not yet provided any official legal basis for the killing (to be fair, some law and policy blogs, such as Lawfare, Just Security, and Articles of War, have begun to address it). This disregard is problematic, as there are indeed serious questions as to the lawfulness of this strike – and people should be demanding answers.

Let us acknowledge up front that Ayman al-Zawahiri was the second-in-command of al-Qaeda at the time of the 9/11 terrorist attacks on the United States – which were heinous crimes, terrorist acts, and amounted to an “armed attack” against the United States under international law.

Nevertheless, his killing some 21 years later requires a legal justification under international law. What is more, the drone strike also constituted a use of force against Afghanistan, with which the United States is no longer engaged in an armed conflict – and so that too requires legal justification. This essay briefly reviews the international law regimes that are implicated (leaving aside entirely the domestic law considerations, such as the 2001 Authorization for Use of Military Force), and some of the questions regarding the lawfulness of the strike that arise under each regime – and argues that these questions are important.

The Use of Lethal Force – International Humanitarian Law

Let us begin with the legal authority for the lethal use of force against the individual. To be something other than murder or extra-judicial killing, there must be some basis in law for such use of lethal force. The United States has for decades made the claim that it is engaged in an ongoing armed conflict with al-Qaeda, and that the law of armed conflict, or international humanitarian law (IHL), thus applies and provides legal authority for U.S. strikes against members of al-Qaeda and other associated transnational terrorist organizations (“associated forces,” or “co-belligerents,” according to the U.S. government).

This idea that a state can be in a protracted extraterritorial armed conflict with a terrorist group or non-state actor (NSA), and particularly the implication that the “battlefield” for this armed conflict, and thus the scope of IHL application, extends to wherever members of the NSA happen to be, is itself highly controversial and disputed. The ICRC has noted that such claims blur the lines between armed conflict and terrorism, and thus which legal regime should apply to operations against NSAs, with adverse effects for the integrity of IHL.

Even if one accepts that this is indeed an armed conflict to which IHL does apply, the transnational and extraterritorial nature of the hostilities raise questions as to whether the full body of IHL applies, as in an international armed conflict (IAC), or whether it is the sub-set of IHL reserved to non-international armed conflict (NIAC). In Hamdan v. Rumsfeld, the U.S. Supreme Court famously held that the conflict was a NIAC, and the United States subsequently adopted that view.

Leaving aside those larger questions, and assuming for the sake of argument that the United States is in an armed conflict with al-Qaeda, and that IHL therefore does apply to this strike, there remain complex legal questions. IHL authorizes, or at least provides immunity, for the use of lethal force against certain individuals engaged in the armed conflict. Combatants, typically defined in accordance with the criteria in Art. 4 of the Third Geneva Convention, and Art. 43 of Additional Protocol I (AP-I), are targetable on the basis of their status alone – but that status only applies in an IAC. Under the more limited set of rules governing NIAC, there are no defined “combatants” who are targetable on the basis of their status. And, regardless of whether this is an IAC or a NIAC, al-Zawahiri would not qualify as a combatant pursuant to the defining criteria for combatants in an IAC in any event.

If he was not a combatant, then what was he, and on what basis could he be targeted? The traditional view, based on Art. 51 of AP-I, is that members of an armed group engaging in an armed conflict are in fact civilians, and are thus protected, “unless and for such time as they take direct part in hostilities.” In other words, he could only be targeted if, and while, he was taking direct part in hostilities. As both the ICRC and Supreme Court of Israel have grappled with in some detail, determining what exactly constitutes “direct part” in hostilities, and how long “for such time” remains open, is complicated.

The ICRC has, controversially, endorsed the view that in some circumstances members of armed groups in a NIAC may be deemed to be engaged in a “continuous combat function,” making them targetable on a more continuous basis. But it is important to note that this is still targeting on the basis of function, and only for such time as they continue this function, and not purely on the basis of status as with combatants in an IAC. Efforts to establish a third category of “unlawful enemy combatants” or “belligerents” in a NIAC, who could be either targeted on the basis of status alone or excluded from the protections of IHL altogether, have been widely rejected, including by some courts (although U.S. courts have taken a different view).

What is more, there have been claims made by U.N. Special Rapporteurs (see Alston, Emmerson, and Callamard), among others, that IHL requires some degree of transparency and accountability in demonstrating how such determinations are made. In other words, states cannot simply baldly assert, without some evidence and information on how conclusions were reached, that individuals were killed on the basis that they were taking direct part in hostilities or fulfilling a continuous combat function.

The bottom line is that there must be some well-founded determination that the 71-year-old al-Zawahiri was either taking direct part in hostilities at the time that he was killed, or, under the more controversial position, that he was still engaged in a continuous combat function. Michael Schmitt has recently argued that he clearly was, but the United States has yet to clearly make the case. Notwithstanding longstanding claims by the United States to the contrary, under the well-established and widely accepted understanding of IHL he cannot be targeted simply because of his status as a “member of” al-Qaeda. That is simply not a status that makes him targetable under IHL, and absent a determination that he was taking part in hostilities or fulfilling a continuous combat function, he is explicitly protected from targeting under IHL.

The Use of Lethal Force if Not IHL

To conclude the analysis of law governing the use of lethal force against the individual, it should be clear that in the absence of an armed conflict and the operation of IHL, then both domestic criminal law and international human rights law apply. The standard for the use of lethal force, as either a justification for violating the right to life under human rights law, or as a defense to allegations of murder under domestic criminal law, are obviously much higher under both. They typically require evidence of imminent threat of death or grievous bodily harm, either to the user of force or to others who the user of force is defending (see Melzer’s seminal text on targeted killing for a detailed law-enforcement paradigm analysis). But here too, there is no legal authority in international law to simply kill terrorists based on their membership in a terrorist organization, or their status as “terrorists.”

The U.S. government has long taken the position that its human rights obligations under the International Covenant on Civil and Political Rights (ICCPR), including the right to life, do not apply extraterritorially. In other words, it could not be held responsible for a violation of al-Zawahiri’s right to life because he was not “within the territory and under the jurisdiction” of the United States. Harold Hongju Koh, when Legal Advisor to the State Department, famously but unsuccessfully argued for a change to the U.S. position on this interpretation of the ICCPR, to bring the United States into line with most of the rest of the world. The European Court of Human Rights has held (albeit under the European Convention of Human Rights, rather than the ICCPR), that the act of killing a person may bring them within the jurisdiction of the state for purposes of implicating human rights obligations.

Related to the question of which law applies is the status of those who killed al-Zawahiri. Initial reports indicate that this was a CIA operation. It is not entirely clear what that means in terms of who actually pulled the trigger, so to speak – the CIA has engaged in joint operations with both the Air Force and Special Forces in the past. But what is clear is that members of the CIA are not part of the armed forces of the U.S., and thus do not enjoy the status of combatant in an armed conflict. They do not enjoy the combatant privileges and immunities. Put simply, the CIA has no legal authority or immunity under IHL to engage in killing, and those who did the killing could be prosecuted or held liable for it. Put another way, IHL would not apply, but rather domestic law and international human rights law would operate in relation to their conduct.

The Use of Force Against Afghanistan – The Jus ad Bellum Regime

There is an entirely separate issue of whether the use of force against Afghanistan violated international law, governed by the jus ad bellum regime. The claim that the United States is engaged in an armed conflict with al-Qaeda has no bearing on the use of force against Afghanistan. If the United States was already engaged in an international armed conflict against Afghanistan, as it was in 2001-02, then the strike could be argued to be simply part of those hostilities. Similarly, if the United States was engaged in a non-international armed conflict within Afghanistan, with the consent of the Afghan government, as it was for the last two decades, then the strike could have been explained as being part of those hostilities, so long as it was within the scope of consent provided. But the U.S. withdrew its forces from Afghanistan last year, and President Biden claimed in August of 2021 that the war there was over. The United States was not involved in any armed conflict with or within Afghanistan in August 2022, until the strike against al-Zawahiri.

There being no ongoing armed conflict with Afghanistan, a use of force against or within the territory of Afghanistan requires legal justification. There can be little question that a missile strike from a drone that kills people within the territory of a state constitutes a use of force against that state, unless the state has consented to the strike. The Taliban regime, the de facto and effective government of Afghanistan, apparently did not consent, and it has indeed condemned the action. (Some have suggested that perhaps there was secret consent, but even in that unlikely event, there are questions about and critiques of the legal validity of such “secret” consent to the use of force).

As most readers are aware, the use of force without prior consent of the target state is prohibited under Art. 2(4) of the U.N. Charter, unless it is either authorized by the U.N. Security Council pursuant to Art. 42, or the action is an exercise of self-defense against an armed attack, under Art. 51. There are differences in opinion (covered by Ruys in his seminal text) over whether such armed attack has to have already occurred or is imminent, but for the sake of argument here, let us assume it extends to “imminent armed attacks.”

Clearly this was no act of self-defense in response to any threat posed by Afghanistan itself. Rather, if self-defense is claimed, then it was self-defense against some armed attack by al-Qaeda. There is considerable controversy over whether states may use force against members of NSAs within the territory of a non-consenting state, on the grounds that the NSA was engaged in some ongoing or imminent armed attack against the defending state, and the territorial state was either unwilling or unable to prevent the attacks.

This “unwilling or unable” doctrine, asserted by the United States and several of its western allies, lowers the threshold for the exercise of self-defense, expands and distorts the notion of imminence, and weakens the principle of necessity in ways that some argue seriously undermine the traditional doctrine of self-defense. I have myself critiqued the doctrine in the past, and have argued that at a minimum the defending state must actually demonstrate (not merely infer) that the territorial state is indeed “unwilling” to prevent an actual or truly imminent armed attack. Many states, particularly in the Global South, have voiced explicit opposition to the doctrine and challenged the claim that it represents customary international law.

But even if we assume for the sake of argument that the “unwilling or unable” doctrine could apply here, the strike against al-Zawahiri does not satisfy even the most expansive formulations of that doctrine. First of all, it is not clear that the United States is claiming self-defense as a justification for the strike. No Art. 51 letter has yet, as of this writing, been filed with the U.N. Security Council, as is required upon the exercise of self-defense. The Art. 51 letter notifying the Security Council of use of force against Afghanistan in October, 2001, in response to the 9/11 attacks, cannot plausibly cover this use of force, some twenty one years later, and after the U.S. government announced that that conflict was over. No other government statement has formally invoked self-defense as a justification for the strike. It is, indeed, quite concerning that no legal explanation or rationale has so far been offered. It is disturbingly reminiscent of the Trump administration’s disregard for any need to explain military strikes against Syria or targeting Iranian Qods Force Commander Qassem Soleimani in Iraq.

Moreover, there has to be some evidence that al-Zawahiri and al-Qaeda were engaging in the preparation of an armed attack of some form. While the U.S. formulation of the doctrine purports to strip the concept of imminence of all temporal meaning, that interpretation is an outlier position within the international community—and in any event, even on its own terms it still requires that there is actual intelligence regarding a real threat of future armed attack.

Yet the U.N. Security Council issued a periodic report on the activity of ISIL and al-Qaeda not two weeks before the strike, in which it concluded that “Al-Qaida is not viewed as posing an immediate international threat from its safe haven in Afghanistan because it lacks an external operational capability and does not currently wish to cause the Taliban international difficulty or embarrassment.” The U.S. intelligence services may have come to different conclusions, but again, transparency and accountability require that the United States explain its position to the international community.

It is also not at all clear that the Taliban government of Afghanistan was “unwilling or unable” to address the threat. Many will argue that al-Zawahiri’s very presence in Kabul represented a violation of the core commitment in the recent Doha agreement between the Taliban and the United States that brought the armed conflict to an end, and that this as such represents evidence that the government would be unwilling to address the threat. But as I and others have argued, speculation and inferences are not sufficient. There is some onus on the defending state to consult with the territorial state and determine that it is actually “unwilling” to address the threat or permit the defending state to do so, unless there is some compelling operational reason that militates against such consultation.

Even the famous “Bethlehem Principles” in support of the “unwilling or unable” doctrine, suggest that there is a presumption that good faith efforts must be made to seek consent from the territorial state, unless certain conditions make it operationally impractical or excessively risky. It might be argued, for instance, that such conditions existed in the case of the strike against Bin Laden. But in the absence of any evidence of any real imminent threat posed by al-Zawahiri, it is unclear that necessity required a use of force without any consultation with the government of Afghanistan.

What’s at Stake

The foregoing does not purport to prove that the strike was unlawful as a matter of international law. But it does lay out the legal regimes that govern this conduct, and raises serious questions that need to be addressed in order to establish that both the killing itself, and the use of force against Afghanistan, were not violations of international law. American media and punditry should be demanding answers to these questions.

The onus is on the United States to demonstrate to its people and to the rest of the world that this strike was not unlawful. President Biden claimed that “justice was served” with this strike, but for a country that purports to be a country of laws, and one that stand for the rule of law, it must be shown that the action was also lawful. Otherwise, it is mere revenge, not justice.

There is a real risk that this action, like the killing of Soleimani, will be seen as the action of a hegemon taken in utter disregard for the laws that it demands that others obey. With the war raging in Ukraine, and claims of Russian war crimes and the crime of aggression much in the news, perceptions of double standards in the operation of IHL and the jus ad bellum regime put the international rule of law at risk. There is much at stake here. This killing must be explained.