Drone Strikes, Military Advantage, and Armed Conflict


| Jul 18, 2022

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In my new book Drone Strike: Analyzing the Impacts of Targeted Killing, I review evidence about the impacts of U.S. targeted strikes outside war zones on Al Qaeda and associated forces (“Al Qaeda”), as well as civilians, over the last 20 years. This evidence includes more than 60 empirical studies, along with Al Qaeda correspondence in the extensive online repository maintained by the Combating Terrorism Center at West Point. All this material indicates that strikes during this period had no discernible effect on the growth of Al Qaeda as a whole or the number of attacks that the organization conducted. Strikes did reduce terrorist activity for up to a few weeks in locations where they occurred, but enduring effects appear to require an intensive strike campaign over an extended period that may not be feasible in most cases.

Evidence does suggest, however, that strikes against top Al Qaeda Core (AQC) leadership in the Federally Administered Tribal Areas (FATA) in Pakistan helped reduce the threat of attacks in the United States. This is because AQC has consistently been the component of Al Qaeda that has insisted on the priority of conducting attacks on the United States to induce it to withdraw from the Islamic world. Attacks on AQC inflicted losses and induced changes in operations that reduced its ability to plan and coordinate these attacks, and to train people to conduct them from a relatively safe haven.

The United States has regarded itself as engaged in an armed conflict against Al Qaeda since 2001. From the perspective of the law of armed conflict, however, the different impacts of strikes that I describe mean that not every targeted strike against Al Qaeda will necessarily produce a military advantage. As a result, not every strike will meet the requirements of jus in bello necessity and proportionality. This suggests that it may be time to rethink whether the United States is justified in continuing to regard its operations against Al Qaeda as an armed conflict.

Military Advantage and Armed Conflict

To appreciate why the armed conflict paradigm may no longer be appropriate, we need to consider the assumptions that underlie the concept of anticipated military advantage during such a conflict. This concept assumes that military operations inflict losses on an adversary that degrade its ability to prosecute the conflict, which ideally results in its defeat as soon as possible.

The idea that the United States is in an armed conflict with Al Qaeda rests on the notion that that group’s leadership has repeatedly expressed its intention to attack the United States and has demonstrated its ability to do so. On this view, Al Qaeda is the equivalent of an enemy whose military forces are organized and dedicated to carrying out a war against the United States under the direction of its top command.

This assumption means that winning this war requires the United States to conduct hostile operations against Al Qaeda in various locations around the world, to deprive it of resources to prosecute the conflict until it can no longer do so. Any strike anywhere that contributes to this erosion of Al Qaeda military strength therefore serves a military advantage. In particular, strikes against Al Qaeda military leaders deprive the organization of people on whom lower-level members rely for instruction in conducting attacks. In contemplating a strike against such leaders, the anticipated military advantage is eliminating key personnel whom Al Qaeda needs to prosecute the conflict.

The findings in my book, however, call these assumptions into question.

The claim that a strike against any military leader achieves a military advantage is reasonable when an adversary is a traditional hierarchical organization such as a State military force. Broadly speaking, decisions made in such an organization at the strategic level determine activities at the operational level, which in turn determine tactical activities. While personnel inevitably exercise some discretion at each level, this is significantly circumscribed by decisions at higher levels of command. Resources are allocated in accordance with these decisions.

Terrorist groups such as Al Qaeda, however, tend to be structured as networks in which leadership provides broad guidance and local groups and cells have considerable autonomy to determine whether, when, where, and how to conduct attacks. As Daveed Gartenstein-Ross and Nathaniel Barr observe, “From the outset, al-Qaeda adopted a unique organizational design, whereby its senior leadership outlined a strategic course for the organization as a whole, but empowered mid-level commanders to execute this strategy as they saw fit.” Local groups are not dependent for resources on network leadership, but develop their own sources of revenues through a variety of activities. Networks also tend to have several redundancies such that the loss of any particular individual in a local cell may not affect the operation of the network as a whole.

If we think of the enemy as Al Qaeda as a whole, these structural features of the group mean that the loss of one or more leaders from a strike may have no meaningful impact on the overall organization’s ability to prosecute an armed conflict. In this sense, a strike may not produce a military advantage because it does not contribute to the defeat of the enemy. This explains why evidence indicates that twenty years of strikes have not reduced the capabilities of Al Qaeda as a whole.

As I have described, evidence indicates that strikes in a particular area may temporarily reduce the ability of a local Al Qaeda group to conduct hostilities in that location. This typically will not prevent it, however, from renewing hostilities a few weeks afterward. The anticipated military advantage in this case is temporary degradation of enemy capabilities in a particular location. This may have no impact, however, on attacks conducted by the overall network. It may not even contribute to winning a conflict defined in local terms, unless there are ongoing strikes coupled with other measures that reduce the appeal of extremism in that area. We therefore cannot automatically assume that strikes that inflict losses on the enemy will degrade its ability to prosecute the conflict.

We could frame military advantage not as contributing to the defeat of Al Qaeda in an armed conflict, but as reducing the ability of Al Qaeda to conduct major attacks in the United States. Indeed, this is the underlying legal rationale for claiming that the use of force against Al Qaeda is an exercise of U.S. self-defense. The evidence suggests that strikes against AQC in Pakistan likely helped accomplish this goal. These strikes therefore achieved a military advantage for the United States, although they did not contribute to “defeating” Al Qaeda. With respect to the conflict as a whole, evidence suggests that strikes redirected terrorist attacks away from the United States and the West to other parts of the world. They thus redistributed, rather than reduced, overall attacks.

As I describe in my book, further attacks against AQC may not appreciably further reduce the threat of attack in the United States. Leadership is now more dispersed, and the network is even more decentralized. AQC has fewer resources to induce local affiliates to conduct attacks against the United States and does not have a safe haven in which to plan and train people for such attacks. This assessment could change, however, if AQC is able to acquire a safe haven in Afghanistan under the Taliban.

The upshot of all this is that we now have evidence that it is misguided to continue to view Al Qaeda as a unified enemy in an armed conflict with the United States. More realistic is to see it as a decentralized network of diverse groups with different capabilities and intentions, loosely guided by top leadership. Most of these groups are focused on local concerns, not on attacking the United States. Top leadership is intent on attacking the United States, but its ability to act on this intention is subject to significant constraints.

In other words, Al Qaeda is less akin to an integrated organization that has the intention and capability to attack the United States, and more a network whose elements may at times have such intention and capability. One or more elements periodically may pose a threat serious enough to warrant a forcible response.

This suggests that it may be more appropriate to view strikes not as operations during an armed conflict, but as discrete uses of force in self-defense. This is essentially the approach that the Obama administration established in its Presidential Policy Guidance (PPG) as a matter of policy – although not law – for strikes outside areas of active hostilities: that a target pose an “ongoing imminent threat to US persons.” As the evidence indicates, strikes can vary in the extent to which they have any impact on terrorist activity. Relying on something akin to the PPG standard would limit strikes to those that are likely to produce an advantage because they reduce a serious threat to the United States.

Legal Implications

A self-defense paradigm would require the United States to squarely address an issue it has been able to avoid by relying on an armed conflict model: even if a strike satisfies jus ad bellum requirements for state self-defense, what body of law should govern the use of force in the operation itself?

There was some discussion of this question about a dozen years ago, but those who referred to self-defense outside armed conflict never suggested a clear answer. Kenneth Anderson, for instance, proposed “customary self-defense” as a basis for targeting outside armed conflict, and State Department Legal Advisor Harold Koh said that “a state that is engaged in an armed conflict or in legitimate self-defense is not required to provide targets with legal process before the state may use lethal force” (emphasis added).

Critics found two problems that they regarded as implicit in Anderson’s and Koh’s reference to the doctrine. The first was that the way Anderson articulated this concept seemed to assume that jus ad bellum standards should govern the use of force on the operational level in individual strikes.

This has some plausibility as a substantive matter. One might argue that jus ad bellum and human rights law share the philosophy that lethal force must be used only when necessary to neutralize a threat. Customary self-defense differs from traditional human rights law, however, by focusing on State, rather than individual, self-defense. This could provide for more flexible applications of the principles of necessity and proportionality than under international human rights law (IHRL). For those who would prefer operational rules less permissive than the law of armed conflict (LOAC) but more attuned to State self-defense than IHRL, relying on jus ad bellum requirements may have appeal.

As Geoffrey Corn noted, however, this formulation conflates two analytically separate doctrines. Jus ad bellum determines whether a State may resort to force, but not how it may use it. The former is meant to protect against violation of State sovereignty, not to regulate the use of force on the operational level. Furthermore, ad bellum and in bello requirements have always been treated as distinct based on the view that States are subject to the latter regardless of whether they satisfy the former.

A second criticism expressed concern that a State might claim that “once it is justified to use force in self-defence, IHL and human rights law would not be applicable to that use of force.” Some argued that the Obama administration’s assertion of self-defense as a legal basis for targeting distinct from armed conflict reflected this assumption. The administration never explicitly adopted this highly questionable position, but treating operations against Al Qaeda as part of an armed conflict meant there was little incentive to elaborate on what customary self-defense might entail.

Assuming that jus ad bellum requirements will not be applied at the operational level, the most common view in the international community is that the use of force is governed by binary alternatives: LOAC and IHRL. Any use of force outside an armed conflict therefore is subject to human rights standards.

The United States, of course, maintains that its human rights obligations under the International Covenant on Civil and Political Rights do not apply outside its borders. Department of Defense Directive 2311.01 provides that in military operations outside of armed conflict, “Members of the DoD Components will continue to act consistent with the law of war’s fundamental principles and rules, which include those in Common Article 3 of the 1949 Geneva Conventions and the principles of military necessity, humanity, distinction, proportionality, and honor.”

One reason the United States resists extraterritorial human rights obligations likely is that it regards IHRL as too restrictive to regulate the exercise of State self-defense outside armed conflict. Observers such as Kenneth Watkin and Monica Hakimi have noted, however, that IHRL provides flexibility to use the level of force necessary to effectively neutralize a threat. It also recognizes that there may be some situations in which capture is infeasible and lethal force is justified. Nor does IHRL absolutely prohibit unintentional harm to innocents in all cases.

At the same time, the paradigmatic focus of IHRL is on temporally immediate threats to individuals rather than to States. This places emphasis on urgent circumstances in which it is necessary to use force to avert near certain death or grievous bodily injury. Discomfort with this conception of a threat has led the United States to formulate a standard of imminence for resort to force in self-defense that is less tethered to temporal immediacy. It may regard a similar reformulation as necessary with respect to IHRL on the operational level for strikes against terrorists planning an attack on the United States. This could be plausible, but likely would be controversial given of criticism of the United States’ standard of imminence for resort to force.

A second view is that a State should be able to determine whether it is necessary for effective self-defense in a given operation to use force subject to LOAC. Geoffrey Corn, for instance, has argued that if a State decides that it needs to use military force to respond to a threat from a transnational terrorist organization, this generally means that the law of armed conflict will govern the operation.

The conventional view, however, is that LOAC is triggered only when the criteria for an armed conflict are satisfied. With respect to armed conflict not of an international character, such as a putative conflict with AQ, these include the existence of hostilities of sufficient intensity between well-organized parties. Critics may can argue that permitting the use of force under LOAC when these criteria are not met effectively means that States, rather than international law, would determine when they can use force under the expansive permissions of LOAC.

One possibility could be for a State to argue that its use of force constitutes the initiation of an armed conflict limited by the scope and duration of the operation. This might be plausible in some cases when a strike is in response to an armed attack. Another is that in the absence of a prior armed attack, the strike itself could be deemed to initiate and conclude an armed attack subject to LOAC. This “first strike” theory, however, is conventionally limited to international armed conflicts.


Where does this leave us? Evidence of the impact of strikes, along with more sophisticated understanding of Al Qaeda’s structure, indicate that relying on a self-defense paradigm outside of armed conflict would help ensure that strikes produce the benefit of reducing a threat of attack on the United States. Consistent with its commitment to the rule of law, the United States would need to be clear about what rules govern the use of force in self-defense at the operational level. Despite what reliance on purely conceptual logic may suggest, my discussion above indicates that none of the alternatives is free of difficulty as a practical matter. It is therefore time for lawyers and scholars to resume the brief conversation that began a dozen years ago, in order to analyze in more depth the legal implications of relying on the right of self-defense to addresses terrorist threats.


Mitt Regan is McDevitt Professor of Jurisprudence and Co-Director of the Center on National Security at Georgetown Law Center, and Senior Fellow at the Stockdale Center on Ethical Leadership at the United States Naval Academy.


Photo credit: Lt. Col. Leslie Pratt