Mitt Regan’s Drone Strike – Analyzing the Impacts of Targeted Killing and the CHMR-AP

by | May 22, 2023

Targeted killing CHMR-AP

Mitt Regan, a widely respected Georgetown University Professor of National Security Law, has written a very timely and thought provoking book, Drone Strike—Analyzing the Impacts of Targeted Killing. This book reviews the available empirical evidence on the impact and effectiveness of U.S. drone strikes outside of “war zones” in order to assess how effective they have been as a counterterrorism tool, and what their impact has been on civilians. Published in the aftermath of the return of power of the Taliban in Afghanistan in August 2021, it provides a valuable assessment of a means of warfare that has dominated the legal and policy discourse for the past 20 years. It also opens a window to see what role quantitative and qualitative evidence may play in the future regarding targeting in general. As Professor Regan indicates “[u]nderstanding what targeting is and is not able to accomplish, and at what cost to whom, can help ensure that policy decisions and normative judgements are as fully informed as possible” (p. 3). Importantly, he notes his conclusions “may both please and displease critics and supporters of targeted strikes” (p. 12).

The timeliness of this book is highlighted by the August 22, 2022 release by the U.S. Department of Defense of its Civilian Harm Mitigation and Response Action Plan. That plan “identifies how DoD will systemically improve our approach to civilian harm mitigation and response.” In doing so it indicates DoD doctrine has “generally not sought to define the ‘civilian environment’ as such and to describe how it can be affected by military operations” (Objective 3, p. 9). The Plan envisages the establishment of a Civilian Protection Center of Excellence with responsibility to “track and conduct cutting-edge analyses of harm data and advise DoD leaders of critical trends; manage an analytical agenda based on operational priorities …” (Objective 2, p. 6), as well as the development of standardized civilian harm operational reporting and data management (Objective 6, p. 17). Professor Regan’s book identifies some of the types of data and studies available to such a Center of Excellence.

The book is divided into three parts comprising 12 chapters. Part I looks at research into the impact of non-U.S. strikes, particularly Israeli attacks during the Second Intifada, to consider the effectiveness of the targeting campaign and what lessons it might have “for the US and for reliance on targeted strikes more generally” (p. 7). Part II examines the effect of U.S. strikes against Al Qaeda and associated groups. Al Qaeda is viewed as including only the top Al Qaeda leadership such as al Qaeda core, but also Al Qaeda in the Arabian Peninsula and Al-Shabaab in Somalia. The associated groups include collaborating ones such as the Tehrik-i-Taliban Pakistan and the Jemaah Islamiyah in Indonesia. This analysis of the quantitative and qualitative research looks at both the immediate and long-term effectiveness of the campaign and, importantly, “how these lessons should guide future deliberations about whether and how to use targeted strikes against Al-Qaeda and other terrorist groups” (p. 8). Part III looks at the effects of targeted strikes on civilians, examining: the challenge in obtaining accurate data; the estimates by nongovernmental organizations; the necessity to consider institutional process as well as technological capability in order to attain true precision; and the physical, social and psychological impacts of strikes on local populations and their attitudes.

The Law of Armed Conflict

What is striking about the book is that so little time and attention is spent by the author on the law when much of the dialogue over the past 20 years has been about the lawfulness of drone strikes, and who qualifies as a legitimate target. For a lawyer untrained in empirical research, such as myself, delving into an analysis of quantitative and qualitative studies can be challenging. However, the indeterminate and often contradictory nature of the past and present legal dialogue regarding targeting makes that effort all the more necessary. It is here that this book is most educational. The reader will be struck by the number and variety of quantitative studies, their methodological approaches and their findings relating to a narrow aspect of targeting. The qualitative studies vary in depth and analysis, but it is noted they provide “unique insights into what, if any, impacts strikes had on terrorist groups” (p. 163).

There is no need for a spoiler alert as this review will not detail the book findings. That is for its prospective readers to explore. However, Professor Regan rightly notes that unexamined assumptions tend to generate sweeping claims such that the strikes have failed to reduce the risk of further attacks, that they are the reason there has been no large-scale attack over the past 20 years, that civilian casualties far exceed militant deaths, or that none are killed by such precision strikes. Another assumption is that local resentment caused by the strikes enhance terrorist recruiting, or conversely, they are welcomed because terrorists are killed who threaten the local community. Regan argues “[t]his book suggests that the truth is more nuanced than any of these claims,” and “my conclusions do not completely vindicate either the critics or supporters” (p. 365). Rather it is necessary to “squarely confront difficult trade-offs and wrestle in clear-eyed fashion with the weight to assign to diverse sets of values” (pp. 365-66).

While focused narrowly on specific types of attacks (drones) against a discrete target set (jihadists), Drone Strike—Analyzing the Impacts of Targeted Killing, highlights the challenges posed more generally to legal advisors, military commanders, humanitarian and human rights advocates, non-governmental organizations, and political leaders when seeking to critique or support the legal framework that has been developed to govern targeting. Unfortunately, the contemporary legal discussion is missing the type of data and analysis that can frame a more nuanced consideration of the legal rules. It is here that The Civilian Harm Mitigation and Response Action Plan, and with it the types of studies identified by Professor Regan, may provide the most benefit to the extent they make available additional, objective, data-driven information to planners, decision makers, and ultimately those critiquing them concerning the conduct of attacks across the armed conflict spectrum.

Having this additional information available will make for a better informed assessment of the legal requirements set out in Article 57(2)(a) of Additional Protocol I, which contain principles widely viewed as reflecting customary international law. Among those requirements is that those who plan or decide upon an attack “take all feasible precautions in the choice of means and methods of attack with a view to avoiding, and in any event minimizing, incidental loss or civilian life, injury to civilians and damage to civilian objects” (emphasis added). It is difficult to see how that obligation can be met without an objective assessment of how to measure such casualties and damage in the context within which the attacks occur.

The CHRMR-AP and the “COIN Hangover”

In its short life The Civilian Harm Mitigation and Response Action Plan has garnered considerable support (see here, here, here, here, and here), but also criticism (here, here, here, and here).  The criticism has been varied including that the Plan will impose inappropriately narrow restrictions on targeting, “create extra layers of bureaucracy for planners and operators to navigate, and that it won’t work in a large-scale conflict.” Further, “the intensity of conflict is not going to allow for exquisite, centralized analysis for the prosecution of each and every target.” A particular criticism is that the Plan finds its genesis in the unique counterterrorism/counterinsurgency focused environment of the past two decades. Instead, the attention of the contemporary commander is, or at least should be, on what is termed “near peer” hostilities. Conflict unencumbered by what two senior U.S. military lawyers have referred to pejoratively as the “corrupting influence” of counterterrorism and counterinsurgency (COIN), and the “COIN hangover.”

A common thread throughout much of the criticism appears to be that restrictive counterterrorism and counterinsurgency policy decisions have overly restricted what would have been allowed through straight legal interpretations. In effect, the application of international humanitarian law or the law of armed conflict unencumbered by such policy decisions would provide commanders greater operational room to maneuver in a high-intensity, large-scale inter-State conflict. Certainly, there are circumstances where that could be the case. The challenge is that this view of the law and its application in armed conflict faces some significant headwinds from both practical and theoretical perspectives. Indeed, one of the challenges from a strategic perspective is that the potential for inter-State conflict between Russia, China, the United States and other Western countries has to be balanced with existing conflicts such as the now 40-year shadow war between Iran and the United States, Israel, and Saudi Arabia, as well as the expanding conflict against jihadist groups in the Sahel Region and elsewhere in Africa.

The focus on near-peer conflict is a product of what is anticipated to be the new cold wars between West and Russia and China respectively. However, lessons can be learned from the first Cold War. It did not result in the type of inter-State conflict the present pivot to near peer conflict is premised on. As identified by Paul Thomas Chamberlin in his 2018 book, The Cold War’s Killing Fields (pp.1-19), what the 1945 to 1990 period did witness was significant lower-intensity inter-State, guerrilla and proxy conflicts that resulted in over 20 million deaths. In this respect, the problems created by focusing on a near-peer conflict that may never occur could be far more problematic than dealing with a perceived “COIN hangover.”  The “lesser” conflicts are not going to disappear and may in fact intensify as the cold wars of the 21st Century unfold.

Further, there is no inter-State conflict regardless of intensity that will not require some degree of limiting the use of force in particular operational situations, which has prompted criticism of the Civilian Harm Mitigation and Response Action Plan.  Perhaps the most obvious example is during periods of occupation, which the United States itself confronted following its 2003 invasion of Iraq. As Stephen Biddle notes in his 2021 book, NonState Warfare,

since at least 1900 all sound war-fighting systems, whoever adopts them, have had to combine features commonly associated with both “conventional” and “irregular” warfare—the very categories themselves are artificial heuristics that appear in their pure form only as rare extrema on a continuous spectrum in which almost all real actors occupy points somewhere in the middle (p. xvi).

This suggests that openness to navigating the policy and law of armed conflict interface must remain a priority regardless of how an armed conflict is characterized. It is a challenge that will not be made easier by looking at the hostilities through what will undoubtedly be an overly narrow “near peer” conflict lens.

Even more challenging is that the critiques of the Plan appear to be premised on the existence of a level of legal clarity applicable to targeting that simply does not exist. The targeting rules may be easily understood in the abstract as a result of being enshrined in Additional Protocol I.  However, there is a paucity of case law, or even international consensus setting out what they definitively mean regarding implementation. As just one example, it was not until the post-9/11 period that efforts were undertaken to clarify the meaning of a foundational term, “direct participation in hostilities,” which was first introduced in 1977. The resulting 2009 International Committee of the Red Cross Interpretive Guidance on the “notion” of direct participation in hostilities (DPH) advanced the dialogue on who may be targeted or conversely, who is an uninvolved civilian. However, it failed to attract universal consensus on terms that by their nature are both amorphous and contextually contingent. Resistance to the Interpretive Guidance resulted in part because it is viewed as having defined DPH too narrowly and has suggested applying it in too restrictive a fashion that does not match the realities of contemporary conflict (see the U.S. DoD Law of War Manual, para. 5.8.3, pp 228-32, as well as analysis here, here, here and here).

There is also limited targeting related case law. The 2006 Israeli Targeted Killing Case provides useful guidance on the respective role of courts and commanders in assessing the “zone of proportionality” (para. 56-58). But the court could only offer notional boundaries between situations in which one person shot by a sniper would be seen as proportionate, in contrast to an aerial bombing where “dozens of its residents and passersby are harmed.” It is the hard cases that would exist “in the area between the extreme examples” (para. 46). As Professor Gabriella Blum notes, a German domestic court dealing with the deaths or injury of over 100 civilians during a 2009 attack in Kunduz, Afghanistan is reported to have held there was no “obvious disproportionality in the present case” (p. 161), in effect casting a criminal law shadow on an assessment of targeting. There is also the 2011 International Criminal Tribunal for the former Yugoslavia Gotovina Case dealing with proportionality. However, the methodology relied on by the trial court was rejected the following year on appeal. Observers were left wondering what exactly the test is for assessing a violation of the targeting obligations. A 2012 Inter-American Court of Human Rights decision, Case of the Santo Domingo Massacre v. Columbia, dealt with the issue of whether an attack was sufficiently precise in distinguishing a military target, but did not substantively address the issue of proportionality (paras. 214-29).  Assessed together there has been little concrete or consistent judicial guidance on targeting other than suggesting the outer boundaries of proportionality may, depending on the context, be quite broad.

In terms of legal analysis, the challenge in assessing proportionality is reflected in Thomas Franck’s view that it is “likely to require the awkward balancing of apples and oranges.” Ultimately, it means a difficult value judgement that pits weighing the anticipated concrete and direct military advantage against the incidental civilian casualties and damage arising from an attack. It is a judgment that reflects the genesis of this principle in the Christian moral doctrine of “double effect”. Considering the lack of legal precedent or consensus, it would appear the rules governing targeting are far more normative than proscriptive. In this respect, complying with targeting precautions set out in the Additional Protocols provides a more practical means of ensuring legal compliance, as well as establishing a comfort level for those planning, deciding on and executing an attack. As Geoff Corn and Jim Schoettler have rightly argued “the package of obligations falling under the umbrella of ‘precautions’ is a genuine focal point for civilian risk mitigation in target selection and attack execution” (pp. 788-89).  It is here that Professor Regan’s work sheds light on where data and analysis-based decision making can be most effective. Incorporating available empirical evidence into planning and decision making when applying targeting precautions also serves to better inform any after the fact assessments of a commander’s attack judgements.

To illustrate, a key element in applying the precautions is determining the military advantage to be gained from an attack. A consistent view among the senior military leadership during the Afghan conflict was that the Taliban used “civilian casualties as major propaganda and recruiting tools, reinforcing the perception that international forces were careless about Afghan lives.” As is indicated in Drone Strike—Analyzing the Impacts of Targeted Killing (pp. 339-40), the empirical evidence does not fully support that conclusion. Instead that evidence shows there was a reduction in “residents’ willingness to provide information, to identify military, and to cooperate in other ways,” however, opposition to U.S. drone strikes did not lead to radicalization of the local population, in recruiting, or an increase in terrorist attacks (p. 348).  It is noted “[m]uch of the debate … has reflected reliance on a priori reasoning and unexamined extrapolation from implicit assumptions” (p. 350). In addition, it is stated “[t]he myriad of consequences of full-scale armed conflict for local populations have been well documented, even if they do not receive the attention they deserve.” The development of the Civilian Protection Center of Excellence should provide an opportunity to do just that. Included in that assessment is the impact of targeting in urban environments, an issue that “is usually centred on law and ethics, rather than infrastructure, and the basis for the expanded or constricted use of explosive weapons tends to be laid more by lawyers, social scientists and military planners than by engineers.” The consideration of such studies and data introduced from outside the military and legal community could advance the targeting process in a way that is readily applicable at an operational level Combined Air Operations Centre that plans, monitors, and directs an aerial campaign.

The impact of targeting on the local population’s willingness to provide information also highlights an aspect of the targeting provisions that receives inadequate attention. While restrictions “imposed” on commanders are frequently viewed as being policy-driven they can actually be a result of the operation of law. In an intelligence-driven COIN environment information from local sources can be a key aspect of operational success. Getting local cooperation provides a concrete and direct military advantage. The result can be a more restricted use of force arising from the consideration of the military advantage part of the proportionality precaution even before the weighing of incidental civilian casualties and damage. As Geoff Corn has noted in the application of the precautions, context matters.  Concern over maintaining the support of the local population is generally not as crucial a factor during more conventional operations, which then could impact on the assessment of military advantage when an attack is being considered.

This is not the only way in which the law rather than policy points to a more calculated and calibrated application of force. Precautions in the attack do not just require consideration that civilian casualties be minimized, but rather avoided altogether. As such Additional Protocol I, Article 57 incorporates a form of minimum force, which is also reflected in different forms in two other major bodies of law relevant to armed conflict, the law governing the exercise of State self-defense (e.g. Article 51 of the United Nations Charter) and international human rights law. As drafted, the targeting precaution appears to require a more restraining effect than how it is often considered. The first requirement is to seek to avoid any civilian injury, death or damage. In other words, to ensure that civilians are not casualties of an attack at all. It is only then, “in any event”, that such effects are to be minimized. In this regard the policy and legal interface needs to be more closely analyzed prior to critiquing The Civilian Harm Mitigation and Response Action Plan.

Concluding Thoughts

Professor Regan’s book provides an enlightening overview of the empirical evidence that has been generated in respect of one narrow aspect of targeting. However, in doing so it points to both the advantages and challenges of using these data in assessing targeting on a much broader scale. In this respect it should be read by both those championing and critiquing the U.S. efforts to mitigate civilian harm in 21st Century warfare, and if it is not already, should be required reading for those establishing the Civilian Protection Center of Excellence.


Ken Watkin served for 33 years in the Canadian Forces, including four years (2006-2010) as the Judge Advocate General.


Photo credit: United States Air Force