Buy Print

Buy Print

Roundtable Book

PDF coming soon


Book Review Roundtable: Leadership Targeting

In this roundtable, Stephen Tankel, Craig Whiteside, Colin Clarke, and Megan Stewart discuss Jenna Jordan's book on the tactic of leadership decapitation of terrorist groups and why some organizations are able to survive leadership decapitation, while others are not.

1. Introduction: No Silver Bullets — The Limitations of Decapitation Strikes

By Stephen Tankel


In the wake of 9/11, President George W. Bush’s administration outlined a mission requiring a massive counter-terrorism campaign that would have been difficult to sell to the American people before al-Qaeda attacked the U.S. homeland. The Bush administration proposed a multi-faceted strategy in which the use of force would be just one part of the U.S. effort to degrade and defeat al-Qaeda and other terrorist groups. In reality, the counter-terrorism campaign that the United States executed in the early years after 9/11 focused overwhelmingly on conducting manhunts, with an emphasis on killing or capturing al-Qaeda leaders. Senior Bush administration officials believed this approach to be “the silver bullet against terrorism.”1 History has shown, however, both benefits and limitations of removing terrorist leaders from the battlefield. In Leadership Decapitation: Strategic Targeting of Terrorist Organizations, Jenna Jordan examines the issue from the perspective of the terrorist groups being targeted. Specifically, she seeks to answer the question of why some organizations survive leadership decapitation — the removal by death or arrest of the leader or high-ranking leadership — and others do not.

Soon after 9/11, the Bush administration embraced a manhunting approach that aimed to take terrorist leaders off the battlefield and extended beyond Afghanistan, where al-Qaeda leadership was based at the time. George Tenet, who served as the CIA director in September 2001, provided Bush with a global counter-terrorism campaign plan in the days following the attacks. It included a worldwide attack matrix detailing operations against terrorists in 80 countries and highlighting states where al-Qaeda leaders might flee during the U.S. invasion of Afghanistan.2 Less than a week after 9/11, Bush signed an order expanding the CIA’s authority to conduct covert operations and use deadly force.3 The Joint Special Operations Command, which integrates different special operations units, was subsequently given authority to go after al-Qaeda and its allies in a number of countries, not always with the host nation’s knowledge or consent.4 The Bush administration also pressed other countries to conduct their own campaigns to capture or kill al-Qaeda members.

President Barack Obama came into office in January 2009 aiming to rebalance U.S. counter-terrorism efforts in two ways. First, he sought to resituate them within a more balanced U.S. national security framework, including doubling down on counter-terrorism partnerships. Second, he placed greater emphasis on non-military instruments of national power, such as ramping up the use of civilian instruments to counter violent extremism. These efforts still remained secondary to reliance on military instruments, which increasingly included “direct action” — the term used to describe air strikes, often by unmanned drones, and raids by U.S. special operations forces outside of conventional war zones. Obama continued his predecessor’s practice of relying on special operations forces, which proved adept at finding, fixing, and “finishing” individual terrorists. Drone strikes became the Obama administration’s primary means of targeting terrorists, especially outside areas of active hostilities.5 President Donald Trump took an even more militaristic approach, reducing reliance on civilian instruments of national power and relaxing the policies and oversight processes governing direct action. The military ramped up its use of direct action in various countries after Trump came into office, while transparency about these operations declined.6

The clear emphasis on direct action naturally led to efforts to assess the usefulness of this tactic, especially against high value targets. Jordan identifies three elements that make terrorist organizations more resilient to leadership decapitation by providing continuity in personnel and support: bureaucracy and organization; popular support; and ideology.7 She uses a mixed-methods approach to support this contention, combining statistical analysis of a dataset of over 1,000 instances of decapitation events against 180 terrorist groups with case studies of Hamas, Sendero Luminoso, and al-Qaeda Central and al-Qaeda Iraq. Jordan uses this combination to identify which types of organizations are likely to be most resilient to decapitation, to explore what explains this resilience, and then to rigorously test her argument. The result is a scholarly contribution with important policy implications: a framework for understanding when leadership decapitation is likely to be more or less successful.

All three reviewers for this roundtable lauded Jordan for her contribution to the field. Craig Whiteside, an expert on the Islamic State movement (which evolved from al-Qaeda in Iraq), laments the emphasis that practitioners and analysts have placed on decapitation, but observes that if we scale down our expectations of what leadership targeting can achieve, there is much to be gained from absorbing what Jordan has produced. Of course, even the most comprehensive books have gaps. Whiteside and Colin Clarke both expressed interest in a deeper exploration of the known unknowns that can arise as a result of killing terrorist leaders. Whiteside specifically notes that delving further into the dynamics of leadership succession in al-Qaeda in Iraq would have reinforced Jordan’s arguments by illustrating how leadership decapitation can backfire. Clarke also ruminated on the ways in which the affiliate model that al-Qaeda pioneered affects the efficacy of decapitation strikes.

Megan Stewart, author of the recently published book Governing for Revolution: Social Transformation in Civil War,8 highlights the messiness of differentiating between insurgent and terrorist groups. Specifically, Stewart argues that Jordan’s work, which she finds compelling, really shows that insurgent movements that use terrorism are more resilient to decapitation than terrorist organizations. In other words, the characteristics that make terrorist groups resilient also make them better defined as insurgent movements. For Stewart, this raises secondary questions about whether decapitation is also a common counter-insurgency technique, and why some straight-forward terrorist organizations are more likely to survive a decapitation effort than others. These are thorny definitional issues that reflect the messiness of the modern terrorism landscape. Jordan does her best to untangle them, and one could argue that her wrestling with the gray areas between terrorism and insurgency is useful in its own right.

Scholars should (and will) continue to debate the definitional questions related to terrorism and insurgency, just as practitioners and analysts should wrestle with the consequences of killing terrorist leaders and the effectiveness of doing so against groups with different organizational models. Stepping back from these important issues to look at the bigger picture, though, it is clear that decapitation is neither a panacea nor an entirely fruitless enterprise. Jordan has provided a useful framework that should inform when it is used.


Stephen Tankel is an associate professor at American University, an adjunct senior fellow at the Center for a New American Security, and an associate editor at Texas National Security Review. He has served on the House Foreign Affairs Committee and in the Office of the Under Secretary of Defense for Policy. Tankel is the author most recently of With Us and Against Us: How America’s Partners Help and Hinder the War on Terror.


2. Making the Mark on Leader Targeting

By Craig Whiteside


Targeting the leaders of organizations has a long history, from the Assassins in the 11th to 13th centuries to more modern-day airpower theories on regime decapitation.9 Leadership matters to all organizations, from states to scout troops, and eliminating effective, experienced leaders has intuitive benefits. The political importance of these discrete events is underlined by the images of U.S. presidents Barack Obama and Donald Trump speaking to international audiences about successful decapitation events — respectively announcing the killings of the leaders of al-Qaeda and the Islamic State — and triumphantly embracing a windfall of political capital.10 Yet, the strategic impacts on these militant groups are minimal, and the groups fight on.

Jenna Jordan’s book Leadership Decapitation: Strategic Targeting of Terrorist Organizations evaluates the impact of contemporary counter-terrorism leadership targeting on militant group longevity using sophisticated statistical modeling. She concludes that this tactic has had mixed results — worse, it frequently backfires. Her conclusion is convincing and compelling, and it properly frames the mediocre results of leadership targeting in its decades of use in counter-terrorism efforts. As important as this research finding is, there are two significant limitations of her study that are worth discussing at length. First is her premise that leadership targeting is central to American policy and supporting strategies designed to defeat terror groups and therefore is a tactic worth evaluating as a proxy to determine the efficacy of the larger enterprise. This premise exaggerates the importance of leadership targeting at the expense of other pillars of the strategy, and therefore measures only small parts of the whole. The other issue is her insufficient treatment of the Islamic State movement, which has been subject to more leadership targeting than any group in history and therefore is a critical case.

The Main Tool, or One of Many?

Samuel Huntington wrote about the dangers of “strategic monism,” a state’s reliance on a single line of effort to defeat an adversary.11 This concept could also apply to academic research and the healthy attention that scholars have paid to the leadership targeting debate between Jordan — who has written several articles evaluating the tactic and is skeptical of its worth — and academics like Bryan Price and Patrick Johnston, who have argued it has more efficacy than is understood.12 This research field has been productive, featured in top journals, and taught widely, and Jordan’s latest contribution is probably the best to date. This said, what we can gain in understanding is limited by the narrowness of the focus on a single tactic in a global effort to manage the impact of militant groups that use terror. Jordan argues instead that leadership decapitation has been central to U.S. counter-terrorism efforts, referring to it throughout the book as a “strategy.” But it is not a strategy. The United States may have relied heavily on manhunting since 9/11 (or even before), but it has never pursued this tactic in isolation nor privileged it over others. Even if one assumes that American policy documents do not fully reflect the realities of U.S. counter-terrorism efforts, they nevertheless reveal a much more comprehensive approach than Jordan suggests.

For example, President George W. Bush’s 2001 National Security Presidential Directive – 9, “Defeating the Terrorist Threat to the United States,” directed the agencies and departments of his administration to “adopt a comprehensive approach employing all instruments of national power and influence in a coordinated manner for a sustained national campaign against terrorism, including its organizations, networks, finances, and access to WMD [weapons of mass destruction].”13 This is a vanilla goal, and a policy that is awkwardly directed at a tactic and is therefore “strategically illiterate,” as Hew Strachan once remarked.14 Emphasized throughout the directive, however, is preventing terrorists from obtaining weapons of mass destruction.15 There is no indication that policymakers believe that leadership targeting is a panacea to solve this complex problem, nor have subsequent documents revealed anything along these lines.

At the strategic level, Secretary of Defense Donald Rumsfeld’s guidance for developing campaign plans to achieve Bush’s policy lists disrupting, damaging, and destroying terrorist organizations by acting against their leaders, forces, support personnel, and networks of state and nonstate supporters as one of eight strategic objectives. This would be accomplished through over a half-dozen “means.” Breaking their networks was merely one specified mean. Of the lines of operations in the coming campaign, only one of the four focused on attacking terror groups. The others were about shaping the international environment to harden targets, eliminating state sponsorship, and freezing assets.16 The use of large-scale counter-insurgency in both Afghanistan and Iraq and the costs of such intense efforts, as well as the growth in terrorist counter-financing capabilities, make arguments about the primacy of leadership targeting in campaigns to defeat terrorist groups unpersuasive. Policymakers might prefer drone strikes and raids like Abbottabad over boots on the ground, but that doesn’t mean that leadership targeting will have more of an impact or that we’ve always chosen this tactic over others.

Leadership Decapitation and the Islamic State Movement

The case studies in Jordan’s book — Hamas, al-Qaeda, and Shining Path — are well chosen, and she uses them skillfully to make several observations based on her extensive global database of leadership targeting of militant groups. She usefully highlights the example of the Islamic State in her conclusion to support her analysis and claims, deservedly so because of its prolific nature and the killing of many of its leaders. As her data show, no group has been on the receiving end of more leadership targeting than al-Qaeda, and particularly its affiliate in Iraq — which began as al-Qaeda in Iraq (AQI) and merged to become the Islamic State of Iraq (ISI) in 2006, changed its name to Islamic State of Iraq and Syria (ISIL) in 2013, and eventually declared itself the Islamic State caliphate in 2014. Its longevity and its impact today on U.S. national security concerns are the best examples of how terror groups shrug off leader targeting, so to speak. Her inclusion of this case in the book is both necessary and critical to her argument. Yet, her treatment of it falls short, largely due to a lack of understanding of the leadership dynamics within the Islamic State movement. She therefore misses a chance to nail home her thesis with this compelling case.

The killing of Abu Musab al Zarqawi — founder of al-Qaeda in Iraq and inspiration for the Islamic State entities that followed — in June 2006 helped the Islamic State movement to transition for the long haul, getting rid of a controversial foreigner and replacing him with an Iraqi-born veteran of the group who was a low-profile bureaucrat with the right credentials. Not only did the killing of al Zarqawi inspire the group to standardize its leadership succession practice and routinize the structure, but it also provided the opportunity for it to shift its management from a loose political front it called the Mujahidin Shura Council (made up of a front of like-minded Salafi groups) into the beginnings of a highly structured Islamic State, beginning in 2006.17 These reforms were crucial to the group’s political survival at a crucial time. When Jordan claims that leadership targeting can backfire, I can think of no clearer example.

Not only did the killing of al Zarqawi trigger the establishment of the Islamic State of Iraq, but the realistic fear of leadership decapitation forced the group to establish a precedent for leadership succession, one designed to imbue legitimacy on the position and not on the individual leader chosen.18 Al Zarqawi was replaced by the bureaucrat Abu Umar al Baghdadi, whose roots as a Salafi preacher before the Iraq invasion, ties to the Prophet Muhammad’s original tribe (Quraysh), and service to al Zarqawi’s early organization in Iraq were the key characteristics of a legitimate replacement for the political leadership laid out in the Islamic State’s doctrinal works. Abu Umar’s replacement, the more infamous Abu Bakr al Baghdadi, met these requirements and was also little-known prior to his selection (and for some time after). The group’s avoidance of charismatic leaders in a maturing organization has been the key to its successful leadership succession practice and the transfer of power from one leader to another.

The importance of a firm leadership succession protocol as the antidote to leadership targeting has been reinforced by the killing of Abu Bakr al Baghdadi in November 2019, and his replacement with the anonymous Caliph Abu Ibrahim al Hashimi al Qurashi. The boldness of refusing to identify the new caliph by name might seem to be a liability, but it reinforces the idea that the legitimacy of the leader derives from the position and not the person.19 The United States recently released the identity of the new caliph to expose his record (and his behavior in detention) to scrutiny, which is an appropriate tactic to counter the deliberate shielding of Amir Muhammad Said Abdal Rahman al Mawla’s identity. At the same time, this release of classified interrogation reports support the Islamic State’s claims that al Mawla is religiously trained, a long-time member of the movement, and a member of a tribe that claims affiliation with the Quraysh.20 The fact that not one of the Islamic State’s outlying provinces renounced its allegiance to the global insurgency following this leadership transition is further proof of the efficacy of the group’s leadership succession principles and their impact on the survival of the movement.21 Leadership targeting certainly has impacted this organization, but like all tactics, the risks can be managed and prepared for by smart organizational practice.

Jordan’s idea that the effectiveness of leadership decapitation can be measured by attacks eschews any emphasis on the important details of leadership succession described above and seems very superficial. Ideological groups like the Islamic State adopt strategies that transcend leaders, as other research has shown.22 Furthermore, the data presented on AQI/ISI attacks is not correct, a problem when the movement is a critical case for analysis. Jordan claims that “AQI carried out 6 attacks in 2004, 68 in 2005, 5 in 2006, and 41 in 2007,” based on claims captured in the Global Terrorism Database.23 Reliance on this database, which has a great reputation but is simply not up for the task of measuring the explosive volume of terror attacks in a multi-sided civil war during these years, is the problem. These numbers differ greatly from AQI/ISI claims during this period.24 It is a difficult problem, but some familiarity with the Islamic State movement case would indicate a massive issue with the data collection here. This period represents the height of the rise of AQI/ISI, which is not reflected at all in these paltry numbers. For example, one study of suicide bombers in Iraq found that only 22 percent of bombings were claimed at all. Of those that were officially claimed, the Islamic State movement claimed 88 percent.25

A look at coalition and Iraqi reporting shows that there was no week from mid-2006 to mid-2007 in which fewer than 1,000 weekly attacks took place from the wide spectrum of militant groups operating in the area, and that in many weeks the number was close to 2,000.26 Considering the U.S. military was close to ceding al-Anbar province to AQI in late 2006,27 it is hard to imagine them doing so to a group that had launched just five attacks across the country that year. My own database of attacks that the Islamic State movement claimed contains 1,104 individual media statements released in 2006 and 932 in 2007. Over 90 percent of these statements were specific claims of one or more attacks — indicating real attack numbers in the thousands, not single digits as reported in Jordan’s depiction of the attacks.

By emphasizing attacks as a measure of resilience to leadership targeting, but then failing to independently collect the attack data necessary to support her claims, Jordan compounds the problems of her treatment of the Islamic State case study. This is too bad, because a better effort here would have strongly supported her overall thesis that leadership targeting is not a game changer when dealing with mature militant groups with a healthy structure, roots within the population, and an ideology that keeps the group cohesive enough to continue the fight into an extended future.


The lengths to which the Islamic State has gone to routinize its leadership succession underscore the unpredictable impact of decapitation strikes as a critical counter-terrorism instrument.28 America’s adversaries have worked hard to protect their valued leaders and prevent their opponents from obtaining the moral victories and political gains that come with successful leadership decapitation strikes. On the one hand, this speaks to the degree to which these groups fear such strikes. On the other hand, it highlights the fact that terrorist organizations continue to find ways to survive despite successful decapitation strikes. Moreover, as Jordan illustrates, some even thrive when their leaders are removed from the battlefield, in ways that are hard to explain but can be seen in the Islamic State’s history.

If we scale down expectations of what leadership targeting can achieve, there is much to be gained from what Jordan has done in this book. Her significant contribution is to expand the theoretical discussion as to when leadership targeting is effective and the conditions under which it might contribute to the defeat of militant groups. To do this, she narrows the many factors that impact militant group survival to three main variables: organizational structure, popular support, and group type or ideology. The database she creates reveals that leadership targeting is often ineffective and, in some cases, backfires by helping the group to solve intractable internecine disputes. In the end, I suspect she is exactly right, and her book is a convincing and well-structured research effort. I would gladly recommend this book as a general example of how to approach a research question using mixed methods.

One of Jordan’s most important observations is that leadership targeting not only has a limited impact on group longevity, but also sometimes assists groups in transitioning into more mature organizations. This is an important concept for policymakers to absorb. The pretense that hardened and exquisitely trained special operators hunting down the country’s enemies will be game-changers in the long struggle against extremist ideologies has evaporated for most. Jordan explains why this is so and hopefully inspires additional research into how these groups can be defeated. 29 The Islamic State’s continued expansion across the globe (especially in Africa) and the Taliban’s victory in Afghanistan is a constant reminder that we have not found a good enough answer to these security challenges.30

Craig Whiteside is an associate professor of national security affairs at the U.S. Naval War College resident program at the U.S. Naval Postgraduate School and researches the Islamic State militant movement. He is a former U.S. Army officer and veteran of the Iraq war.


3. Leadership Decapitation Is No Panacea

By Colin P. Clarke


It is impossible to study international terrorism without reading and hearing repeatedly that the United States cannot kill its way out of the problem. When evaluating the efficacy of leadership decapitation in terms of a broader counter-terrorism or counter-insurgency campaign, it is critical to think beyond targeting individual leaders and to look more comprehensively at how to disrupt terrorist organizations writ large. In my own research on counter-terrorism and counter-insurgency, the preponderance of evidence suggests that it is more effective to disrupt terrorist organizations and insurgent networks by focusing on dismantling supply lines, attacking logistical capabilities, and denying insurgents the ability to enjoy external support from both state and nonstate actors.31 This doesn’t mean that killing high-value targets is ineffective, but rather that decapitation is merely one of many tactics that should be used as part of a wider strategy and that its effectiveness is often likely to be situational.32

Accepting this premise still leaves open the questions of how effective decapitation strikes can be, and under what circumstances they are likely to yield the highest return on investment. In her book Leadership Decapitation: Strategic Targeting of Terrorist Organizations, Jenna Jordan seeks to answer the difficult question: Why does leadership decapitation of terrorist groups work in some cases, but not in others? Jordan’s book is a major contribution to the literature, and she should be recognized for her valuable research and commitment to bringing empirical evidence to bear on such a hotly contested issue. She deftly illustrates that removing high-value targets is not a panacea and, as the central focus of her book, examines when decapitation works, when it does not, and what accounts for variation across cases. There were two primary areas that I wished that Jordan had explored in more detail: the ways in which the new type of organizational approach that al-Qaeda pioneered affects the efficacy of decapitation strikes; and the known unknowns that can arise as a result of killing terrorist leaders.

The Organizational Structure of al-Qaeda

Befitting a scholarly work intended to develop generalizable findings, Jordan explores several different types of terrorist organizations. Taking a broader approach to case selection requires trade-offs when it comes to how deeply she can delve into any one group. All authors face trade-offs, and one can hardly fault Jordan for choosing to explore a broader universe of terrorist organizations. Nevertheless, I was left wanting a deeper dive into how decapitation strikes have affected al-Qaeda given its particularly complex organizational dynamics. Jordan calls al-Qaeda a “meta-organization” because it is “composed of many different and independent organizations and individuals characterized by their level of autonomy and their pursuit of shared goals.”33 I was left wanting more detail on al-Qaeda’s affiliates, especially in terms of how Jordan assesses the effects of decapitation strikes on these organizations and on their relationship to al-Qaeda central.

The first issue that deserves greater attention is the command and control exercised by al-Qaeda leaders. By the time U.S. forces killed Osama bin Laden, the founder and longtime leader of al-Qaeda Central in May 2011, some analysts had written him off as a marginalized figure who spent his time in hiding and had little impact on the day-to-day operations of al-Qaeda’s global network. In reality, despite the suggestions that al-Qaeda’s top command was “isolated and irrelevant,” bin Laden remained an active leader who provided important input on tactics, operations, and strategy for the group.34 As Bruce Hoffman illustrated after reviewing documents found in bin Laden’s Abbottabad compound, the al-Qaeda chieftain remained a hands-on leader until his last days.35 A more focused look at al-Qaeda’s command and control apparatus, especially in periods immediately following decapitation strikes, could have provided more granularity at exactly how impactful these targeted strikes actually were on al-Qaeda’s operational tempo.

Second, and relatedly, although bin Laden may have been a hands-on leader, his actual degree of command and control was limited by al-Qaeda’s organizational structure, which is fundamentally different than ethno-nationalist or secessionist terrorist groups of the past. Thus, removing bin Laden had little impact on al-Qaeda’s affiliates in the Sahel, for example. Jordan’s book, while thorough in many respects, fails to discuss the interplay between the removal of top al-Qaeda leaders and how that impacted the day-to-day operations of the organization. From its earliest days, al-Qaeda proved it could operate as a hybrid entity, with its leadership spread between different countries.36 Both before and after bin Laden’s removal, al-Qaeda’s senior leadership remained involved in planning operations. Mid-level commanders were empowered to execute the organization’s strategic vision as they saw fit.37 Indeed, it was the “group of middle managers” that were able to “provide the connective tissue that links the top of the organization with its bottom and, thus, makes it possible for al-Qaeda to function as a coherent and operationally effective entity.”38 To the degree that targeted killing has been an effective tactic on its own against al-Qaeda, it has been where the United States used it to eliminate potential threats from external operations or to take out broad swaths of the al-Qaeda network, most notably against al-Qaeda in Iraq and al-Qaeda Central in Afghanistan and Pakistan.39 But this is not the same as leadership decapitation.

Third, although not limited to the case of al-Qaeda, the effectiveness of leadership decapitation also relies partly on who replaces the deceased leader, demonstrating the importance of organizational structure and how that is affected by leadership losses at the uppermost echelons. There are several interesting counterfactuals to ponder in the wake of bin Laden’s death, including whether he would have been able to hold al-Qaeda together and prevent the split that led to the Islamic State if he had still been alive. No one knows whether the outcome would have been better or worse had bin Laden survived — these are, after all, subjective concepts — but it does appear that Ayman al Zawahiri has struggled to inspire the same level of allegiance.40 Now that al Zawahiri is in charge, if there is a general consensus among U.S. analysts that he is a completely ineffective leader, then it could make sense to allow him to remain alive despite the desire for rough justice against someone with so much American blood on his hands.

Jordan notes that al-Qaeda and its affiliates were targeted 288 times between 1995 and 2016, although as she concludes, “leadership targeting has been an ineffective strategy against al-Qaeda.”41 She goes on to write that “decapitation has been unable to significantly degrade and defeat al-Qaeda or any of its franchises, and barring the complete breakdown of the group’s structure or support, is unlikely to bring about its defeat.”42 One of her overarching conclusions describes why al-Qaeda has been largely immune from decapitation — the groups that are the most difficult to weaken through this approach are those that are bureaucratized, have substantial communal support, and adhere to an Islamist ideology. Forebodingly, this also describes the Islamic State, suggesting that it, too, may be able to sustain a degree of longevity far beyond the norm for most terrorist organizations.

Known Unknowns

Targeting the leader of a terrorist organization may be temporarily worthwhile and bring certain benefits, but it also leads to a series of second- and third-order consequences, which are something that Jordan could have discussed more in her book. To begin with, decapitation can reshape the composition of a terrorist or insurgent group, and not always to the benefit of counter-terrorism or counter-insurgency forces. As Cynthia Irvin has demonstrated through her research on ethno-nationalist actors, terrorist groups and insurgent movements consist of some combination of ideologues, radicals, and politicos.43 Ideologues are often vehemently against any negotiations and see armed struggle as the only path to victory. Radicals, while preferring violent ends to achieve goals, may be amenable to a political solution if they deem one viable. Politicos, finally, are those within the organization squarely focused on ending the conflict through peace talks or a negotiated settlement if the terms are acceptable. If a counter-insurgent force believes that removing a recalcitrant leader could lead to the ascension of a more moderate figure, it may be worth taking the calculated risk of targeting the more militant leader.

On the other hand, it is possible that leadership decapitation will lead more extreme forces to rise to the fore, or create the conditions for more violent splinter groups to emerge. For example, as I’ve argued in my recent book After the Caliphate, although killing Abu Bakr al Baghdadi was undoubtedly necessary, it could create the conditions for the fracturing of the Islamic State. This, in turn, could lead to the emergence of new, and in some cases more violent and operationally capable, splinter organizations.44 Policymakers, government officials, and military leaders should be prepared to deal with splinter groups as they emerge in the aftermath of what seems to be a relatively successful campaign against the parent group.45 With the Islamic State, these splinters could form their own, new organization, or be absorbed into existing franchise groups in Libya, Afghanistan, Yemen, or elsewhere. Research by Phil Williams and Paul Kan in the field of criminology, building on a concept initially developed by Richard Friman called “vacancy chains,”46 have shown how leadership decapitation efforts against violent drug trafficking organizations in Mexico have resulted in new opportunities for other criminal organizations. Some of them have proven more violent than the original target. Competition to fill power vacuums can also lead to a spike in violence as a “feeding frenzy” between groups eager to move into new territory brings with it battles over control of territory, supply lines, and access to both product and market.47 Jordan’s findings largely track with these conclusions, as she notes that decapitation does not increase the mortality rate of terrorist groups and, in some cases, even leads to more terrorist activity.

Another problem with decapitation strikes is the issue of “intel gain-loss,” or the decision over whether the value of collecting information from an enemy target is more worthwhile than destroying the target itself. If, by monitoring the leadership of a terrorist group, security and intelligence services are afforded an opportunity to gain a greater understanding of the contours of the organization, how it is structured, and how it operates, this could be an argument in favor of eschewing a decapitation strike and continuing to monitor various forms of intelligence, including signals intelligence and human intelligence. This is not to say that valuable intelligence cannot be gleaned from decapitation strikes — it can, especially when collection is focused on reactions within the group to the loss of a terrorist leader. Put simply, the point is that decapitation should not be the default setting, but should be viewed as complementary to other aspects of a well-defined strategy.


Despite the amount of attention paid to the subject of leadership decapitation in both counter-insurgency and counter-terrorism, it remains merely one of many approaches that security forces should adopt. A growing body of research, as discussed above, highlights the importance of targeting an organization’s logistical network, thus disrupting its flow of resources, including manpower, financing, and materiel.48 Terrorist groups seem more likely to survive the elimination of a leader, even a highly charismatic one like bin Laden, than they are to overcome the crippling of their supply infrastructure. This is especially the case when seeking to combat transnational organizations that can rely on a constellation of affiliates and franchise groups — a model adopted by both al-Qaeda and the Islamic State and one that provides the global jihadist movement with a level of resilience that blunts the impact of decapitation strikes.

Too often, leadership decapitation is viewed as a panacea, as policymakers tout the removal of high-value targets to suggest a “turning point” that fails to materialize. It is correct to seek to decapitate terrorist organizations, but these are tactical actions, not strategic ones. If these tactical actions occur without a real strategy, they will have limited impact. Decapitation also fails to address the phenomenon of terrorist groups splintering, unless the proposed solution is to continuously target the leaders of those splinters as well, evoking well-worn clichés of playing “whack-a-mole.”

Finally, leadership decapitation is not a viable tactic when dealing with movements that adopt a “leaderless resistance” model, as pioneered by white supremacist extremists in the United States.49 Nor is leadership decapitation effective against movements and networks like al-Qaeda. One of the conclusions of Jordan’s case study on al-Qaeda is that it is an outlier. In Jordan’s words, “the al-Qaeda case is slightly different, in that al-Qaeda is not only one organization.”50 Yet, other than movements modeled around leaderless resistance and networks like al-Qaeda, there are few major terrorist threats that concern countries like the United States. This means that decapitation is, and may continue to be, of decreasing utility going forward, as other violent extremists adapt their approaches to mimic the organizational structures of terrorist groups that have been most successful in surviving.


Colin P. Clarke, Ph.D., is the director of policy and research at The Soufan Group and a senior research fellow at The Soufan Center. He tweets at @ColinPClarke.


4. Leadership Decapitation: Targets and Scope

By Megan Stewart


Jenna Jordan’s book, Leadership Decapitation: Strategic Targeting of Terrorist Organizations, offers theoretically valuable and policy-relevant insights into the resiliency of organizations that use terrorist tactics. In particular, Jordan focuses on why some of these organizations can survive leadership decapitation — the removal by death or arrest of a group’s leader or high-ranking leadership.51 The book contributes to the scholarly field by providing a compelling framework for understanding the conditions under which leadership decapitation is most likely to be unsuccessful. In specifying the reasons why decapitation fails, the work helps to pinpoint the types of groups that may be less susceptible to decapitation strategies, guiding when and where policymakers should rely on decapitation as opposed to other counter-terrorism tools.

In her analysis, Jordan focuses on three elements that she says make terrorist organizations more resilient: bureaucracy and organization; ideology; and communal support, which is often cultivated through the provision of goods and services. All three mechanisms, according to Jordan, provide continuity in personnel and support that together sustain an organization despite the loss of key leaders.52 First, if an organization experiences decapitation or leadership loss, a well-organized terrorist organization with a bureaucracy typically has clear chains of command that enable specific individuals to quickly and seamlessly transition into leadership roles.53 Second, certain ideologies or group goals do not “depend upon a leader for [their] articulation,” meaning that these ideas and ambitions are already present within the local community.54 The match-up between organizational ideas and goals, and local communities’ ideologies and ambitions creates strong ties between terrorist organizations and communities, integrating the organization and base and generating widespread support. Finally, in the event of leadership targeting, higher levels of communal support for an organization keep the group afloat and provide a steady stream of personnel.55 One central way that terrorist groups can gain this support, according to Jordan, is by providing goods and services to a community.56

To bolster these claims and explore theoretical contentions, Jordan relies on both statistical analyses and case studies. Jordan created an extensive dataset of over 1,000 instances of decapitation events against 180 terrorist organizations.57 Using this dataset, she finds that larger organizations, which may be more likely to have a bureaucracy, and Islamist or religious organizations are more resilient to decapitation.58 She then reviews several case studies of decapitation to analyze how certain factors prevent insurgent collapse: Hamas, Sendero Luminoso, and al-Qaeda (both al-Qaeda Central and al-Qaeda Iraq).

A book that explores an important topic with crucial policy implications, Leadership Decapitation is a welcome and valuable read. By focusing on the failure of counter-terrorism policies, the book not only compliments existing works on organizational theory and institutional resilience, but also has clear real-world application in identifying when decapitation might be effective and why.

When Does Decapitation Happen?

Like any good book, Jordan’s raises a number of important questions. Despite its significant merits, the work leaves unanswered the question of why policymakers rely on decapitation as opposed to other counter-terrorism tools. Policymakers likely do not randomly target terrorist organizations for decapitation, but rather, select specific organizations for decapitation. An understanding of why and when they decide to rely on decapitation is critical to evaluating Jordan’s argument: It is possible that certain types of ideologies or goals provide greater resilience against decapitation, as Jordan argues. It is also possible that terrorist organizations with certain ideologies or goals tend to be targeted with decapitation efforts with greater frequency, allowing them to adapt.

According to Jordan, most of the 1,000 decapitation events from her dataset occurred against just nine different organizations, many of which are Islamist or secessionist.59 Other descriptive analyses also indicate that certain types of organizations — Islamist groups, religious groups, and separatist groups — are more likely to be targeted with decapitation.60 Yet, according to Jordan, organizations with these goals and ideologies are also more likely to be resilient to decapitation. If certain types of organizations are more likely to be targeted with decapitation, as Jordan’s research indicates, leaders of these organizations could develop institutional tools to resist decapitation strategies. Knowing that their organization might be especially prone to decapitation events, group members may increase security around leaders or develop clear succession plans to smooth the transition from one leader to another. Such innovations can spread to other groups, with organizations adopting practices and behaviors they think are appropriate, necessary, or effective.61

As a whole, this presents an alternative mechanism to the one Jordan suggests. Islamist, secessionist, and religious groups may not be inherently more resilient to leadership decapitation than other types of groups due to the broader appeal of their ideology. Rather, these sets of groups could have been systematically more likely to be targeted. And this targeting could have led to learning and adaptation about how to be more resilient among these specific types of organizations. Future work might explore the important questions raised by Jordan: When and why does decapitation occur against some groups but not others?

Decapitation of Insurgent or Terrorist Organizations?

A second question Jordan’s work raises has to do with the distinction between insurgencies and terrorist groups. Jordan frames the book around explaining variation in when decapitation is an effective counter-terrorism tool. But the bulk of the case evidence and theory suggests that decapitation is not an effective counter-insurgency tool. In the introductory chapter, Jordan spends an appropriately considerable amount of time describing the differences between a terrorist organization and an insurgency that engages in terrorism.62 Such distinctions are not always straightforward: terrorism, or the targeting of civilians for political purposes, is a tactic. Some organizations rely on terrorism as their modus operandi exclusively or predominantly, others sporadically, and others not at all. Because terrorism is ultimately a tactic that different organizations employ to varying degrees, scholars have to make and justify tough decisions about which cases to include in their analyses.

According to some existing approaches that Jordan cites, terrorist organizations and insurgencies are differentiated by whether they control (or aspire to control) territory.63 Insurgencies and not terrorist groups typically control (or aim to control) territory. When they do, insurgencies are more likely to develop bureaucratic features to manage people and personnel.64 Furthermore, to control territory, insurgencies may have to be reasonably large in size. Finally, when insurgencies control territory, they are also more likely to establish social service institutions.65 By contrast, according to some researchers that Jordan cites, terrorist organizations typically do not control territory. Because they do not control territory, they may be less likely to have bureaucracies, provide services, or develop a large administrative apparatus. Instead, they typically form clandestine cells that operate underground. To maintain underground secrecy, these groups may be small in size.

The distinction between the Islamic State organization in Europe and the Islamic State in Iraq and Syria helps illustrate the distinction between terrorist groups and insurgencies that use terrorism as a tactic. In Europe, the Islamic State formed small, underground cells that would be unable or unwilling to wrest control of territory from Western European governments.66 By contrast, the Islamic State in Iraq and Syria controlled thousands of miles of territory and millions of people across two countries at its peak.67 The organization in Iraq also confronted state militaries conventionally through mobile/guerrilla warfare, developed a robust international propaganda outlet, and developed an extensive governance apparatus.68

Jordan ultimately decides to include in her analysis insurgent organizations that rely on terrorism in addition to terrorist organizations that predominantly or exclusively rely on terrorism.69 This decision has certain trade-offs. Specifically, Jordan identifies some of the same sets of attributes that insurgencies and not terrorist organizations are most likely to develop, often as a function of their territorial control — bureaucracy, service provision, large size — as the attributes most strongly correlated with decapitation survival. The empirical tests then support the contention that these features that are most closely associated with insurgents provide a greater degree of resiliency than those of terrorist organizations that do not control territory and therefore frequently do not develop these characteristics.

In other words, Jordan’s analysis includes insurgencies that typically control territory and occasionally use terrorism to achieve their objectives, and terrorist organizations that never control territory and exclusively or predominantly rely on terrorism to achieve their objectives. Between these two sets of organizations, insurgencies may be more likely to be large with bureaucracies and social service institutions — the very things Jordan argues make organizations more likely to survive decapitation efforts. If insurgencies are more likely to be bureaucratized and provide services, then this suggests that insurgencies are more likely to survive decapitation efforts in comparison to terrorist organizations.

If that is the case, Jordan misses two opportunities to expand the already substantial contributions of her book, but offers much for future research exploration. First, as Jordan deftly demonstrates, states clearly use decapitation against insurgencies. How common is this approach to counter-insurgency, as opposed to counter-terrorism? Why is it used against some insurgencies? Do policymakers think about decapitation against insurgents and terrorists differently? Future research might be able to explain the conditions under which policymakers use decapitation against insurgencies or terrorist groups.

Second, as suggested above, the theory and empirical evidence indicate that insurgencies may be more likely to survive decapitation given that the attributes associated with decapitation failure are often associated with insurgencies. Future research might explore the conditions under which decapitation is more successful when used among terrorist groups specifically (and not insurgencies). And when used against insurgencies alone (and not terrorist groups), when is decapitation more successful (if ever)? Do the same attributes that make insurgencies more resilient to decapitation, but are not usually found in terrorist organizations, apply to terrorist groups as well, or are there other factors unique to terrorist organizations that facilitate their resiliency? Future research might ultimately explore whether analyzing just terrorist groups or just insurgencies reveals similar patterns to those that Jordan found when combining both groups.


As a whole, Jordan offers a number of important theoretical, empirical, and policy contributions: She identifies which types of organizations are going to be most resilient to decapitation, identifies a set of mechanisms that explain this resilience, and then rigorously tests her argument. These findings speak to the organizational resilience of insurgencies and terrorist organizations while proving policy-relevant in their implications and conclusions. Jordan’s work raises a number of important questions, such as when and why decapitation happens and what the distinctions are between terrorist groups and insurgencies. These questions offer a number of promising avenues for future scholarship.


Megan A. Stewart, Ph.D., is an assistant professor at American University. Her book, Governing for Revolution, was published in 2021 with Cambridge University Press and her other research has been published in venues such as International Organization, Journal of Politics, Comparative Political Studies, and the Journal of Conflict Resolution.  


Image: Chabster, (CC BY 3.0)


1 Quote from a former senior Defense Department official, in Sean Naylor, Relentless Strike: The Secret History of Joint Special Operations Command (New York: St. Martin’s Press, 2015), 165.

2 Dana Priest, “Foreign Network at Front of CIA’s Terror Fight,” Washington Post, Nov. 18, 2005,

3 Peter Baker, Days of Fire: Bush and Cheney in the White House (New York: Doubleday, 2013), 148.

4 Naylor, Relentless Strike,169; and Jeremy Scahill, Dirty Wars: The World Is a Battlefield (New York: Nation Books, 2013), 388.

5 For data on drone strikes, see Peter Bergen, David Sterman, and Melissa Salyk-Virk, “America’s Counterterrorism Wars: Tracking the United States’s Drone Strikes and Other Operations in Pakistan, Yemen, Somalia, and Libya,” New American Foundation, last updated June 17, 2021,

6 Stephen Tankel, “Donald Trump’s Shadow War,” Politico, May 9, 2018,

7 Jenna Jordan Leadership Decapitation: Strategic Targeting of Terrorist Organizations (Stanford, CA: Stanford University Press, 2019), 7–8.

8 Megan A. Stewart, Governing for Revolution: Social Transformation in Civil War (Cambridge, UK: Cambridge University Press, 2021).

9 Bernard Lewis, The Assassins: A Radical Sect in Islam (New York: Perseus Books Group, 2003); and Robert A. Pape, Bombing to Win: Air Power and Coercion in War (Ithaca, NY: Cornell University Press, 1996), 211.

10 Nicholas Bowman, Robert Joel Lewis, and Ron Tamborini, “The Morality of May 2, 2011: A Content Analysis of U.S. Headlines Regarding the Death of Osama bin Laden,” Mass Communication and Society 17, no. 5 (2014), 639–64,; and Daniel Byman, “Al-Baghdadi’s Death … and that Presidential Speech,” Lawfare, Oct. 27, 2019,

11 Samuel Huntington, The Soldier and the State (Cambridge, MA: Harvard University Press, 1957), 400, 418–27.

12 The book builds on two of her previous articles in highly respected journals that question the strategic impact of leader targeting and continues a debate with Bryan Price and Patrick Johnston, whose data projects have a more optimistic outlook. Jenna Jordan, “When Heads Roll: Assessing the Effectiveness of Leadership Decapitation,” Security Studies 18, no. 4 (2009): 719–55,; Jenna Jordan, “Attacking the Leader, Missing the Mark: Why Terrorist Groups Survive Decapitation Strikes,” International Security 38, no. 4 (Spring 2014): 7–38,; Bryan Price, “Targeting Top Terrorists: How Leadership Decapitation Contributes to Counterterrorism,” International Security 4, no. 36 (Spring 2012): 9–46,; and Patrick Johnston, “Does Decapitation Work? Assessing the Effectiveness of Leadership Targeting in Counterinsurgency Campaigns,” International Security 36, no. 4 (Spring 2012): 47–79,

13 George W. Bush, “NSPD-9: Defeating the Terrorist Threat to the United States,” The White House, Oct. 25, 2001,  2,

14 Hew Strachan, The Direction of War: Contemporary Strategy in Historical Perspective (Cambridge: Cambridge University Press, 2013).

15 Bush, “NSPD-9.”

16 Donald Rumsfeld, “Strategic Guidance for the Campaign Against Terrorism,” Department of Defense, Memorandum, Oct. 2, 2001,

17 Al Zarqawi’s death, the impetus to form a new political entity, and the criteria in selecting future leaders can all be found in Uthman Bin Abd al Rahman al Tamimi, “Informing the People about the Birth of the Islamic State of Iraq,” al-Furqan Media Foundation, 2006.

18 Haroro J. Ingram, Craig Whiteside, and Charlie Winter, The ISIS Reader: Milestone Texts of the Islamic State Movement (New York: Oxford University Press, 2020), 141–43.

19 Cole Bunzel, “Caliph Incognito: The Ridicule of Abu Ibrahim al-Hashimi,” Jihadica, Nov. 14, 2019,

20 Daniel Milton, “The al-Mawla TIRs: An Analytical Discussion with Cole Bunzel, Haroro Ingram, Gina Ligon, and Craig Whiteside,” CTC Sentinel, 13, no. 9 (September 2020),

21 Haroro J. Ingram and Craig Whiteside, “Caliph Abu Unknown: Succession and Legitimacy in the Islamic State,” War on the Rocks, Nov. 25, 2019; and Haroro J. Ingram, Craig Whiteside, and Charlie Winter, “The Islamic State’s Global Insurgency and Its Counterstrategy Implications,” The Hague: International Centre for Counter-Terrorism, November 2020,

22 James L. Regens and Nick Mould, "Continuity and Change in the Operational Dynamics of the Islamic State," Journal of Strategic Security 10, no. 1 (Spring 2017): 53–80,

23 Jenna Jordan, Leadership Decapitation: Strategic Targeting of Terrorist Organizations (Stanford City, CA: Stanford University Press, 2019), 240.

24 For a compilation of AQI/MSC/ISI claims during these years see Craig Whiteside, “The Smiling, Scented Men: The Political Worldview of the Islamic State of Iraq (2003‒2013), Doctoral Dissertation, Washington State University, 2014,

25 Katherine R. Seifert and Clark McCauley, “Suicide Bombers in Iraq, 2003–2010: Disaggregating Targets Can Reveal Insurgent Motives and Priorities,” Terrorism and Political Violence 26, no. 5 (2014): 803–20,

26 Anthony H. Cordesman, “Iraq and the United States: Creating a Strategic Partnership,” CSIS, June 24, 2010, 14,

27 Alfred B. Connable, “Intelligence Assessment in Late 2005 and 2006,” in Al-Anbar Awakening, Vol 1, American Perspectives: US Marines and Counterinsurgency in Iraq, 2004-2009, ed. Timothy S. Williams and Kurtis P. Wheeler (Quantico, VA: Marine Corps University Press, 2009), 120–37.

28 Ingram, Whiteside, and Winter, The ISIS Reader, 141–45.

29 Audrey Kurth Cronin, How Terrorism Ends (Princeton, NJ: Princeton University Press, 2009).

30 Haroro J. Ingram, Craig Whiteside, and Charlie Winter, “The Routinization of the Islamic State’s Global Enterprise,” The Hudson Institute, April 2021,

31 Christopher Paul et al., Paths to Victory: Lessons from Modern Insurgencies (Santa Monica, CA: RAND Corporation, 2013),

32 For example, Patrick Johnston’s research has found that leadership targeting can be extremely effective along several important indicators, from the duration of an insurgency to the intensity of a conflict and the operational tempo that insurgents are able to maintain. Bryan Price’s research on decapitation strikes demonstrates that the organizational dynamics of terrorist organizations make finding an effective successor a difficult proposition, and many fail to do so. Patrick B. Johnston, “Does Decapitation Work? Assessing the Effectiveness of Leadership Targeting in Counterinsurgency Campaigns? International Security 36, no.4 (Spring 2012): 47–79,; and Bryan C. Price, “Targeting Top Terrorists: How Leadership Decapitation Contributes to Counterterrorism,” International Security 36, no. 4 (Spring 2012): 9–46,

34 Daveed Gartenstein-Ross and Kyle Dabruzzi, “Is Al Qaeda’s Central Leadership Still Relevant?” Middle East Quarterly (Spring 2008): 27–36,

35 Bruce Hoffman, “What Osama Was Thinking at the End,” Wall Street Journal, May 8, 2012,

36 Colin P. Clarke, “Using the McKinsey 7S Framework to Assess Al-Qaeda Over Three Decades,” International Centre for Counterterrorism (ICCT) – The Hague, December 2019,

37 Daveed Gartenstein-Ross and Nathaniel Barr, “How Al-Qaeda Works: The Jihadist Group’s Evolving Organizational Design,” Current Trends in Islamist Ideology, no. 23, June 2018, 84,

38 Peter Neumann, Ryan Evans, and Raffaello Pantucci, “Locating Al-Qaeda’s Center of Gravity: The Role of Middle Managers,” Studies in Conflict and Terrorism 34, no. 11, (2011): 826,

39 Haroro J. Ingram and Craig Whiteside, “Unexamined Consequences: Leadership Decapitation and the Rise of ISIL,” CDA Institute, Summer 2016,

40 Barak Mendelsohn, “Ayman al-Zawahiri and the Challenges of Succession in Terrorist Organizations,” Terrorism and Political Violence, published online Dec. 10, 2020,

41 Jenna Jordan, Leadership Decapitation: Strategic Targeting of Terrorist Organizations (Redwood City, CA: Stanford University Press, 2019), 178.

42 Jordan, Leadership Decapitation, 179.

43 Cynthia Irvin, Militant Nationalism: Between Movement and Party in Ireland and the Basque Country (Minneapolis: University of Minnesota Press, 1999).

44 Colin P. Clarke, After the Caliphate (London: Polity Press, 2019).

45 Ben Connable and Martin C. Libicki, How Insurgencies End (Santa Monica, CA: RAND Corp., 2010).

46 H. Richard Friman, “Forging the Vacancy Chain: Law Enforcement Efforts in Criminal Economies,” Crime, Law, and Social Change, 41 (February 2004): 53–77,

47 Paul Rexton Kan and Phil Williams, “Afterword: Criminal Violence in Mexico—A Dissenting Analysis,” Small Wars & Insurgencies 21, no. 1 (2010): 218–31,

48 See Paul et al., Paths to Victory.

49 J.M. Berger, “The Strategy of Violent White Supremacy Is Evolving,” The Atlantic, Aug. 7, 2019,

50 Jordan, Leadership Decapitation, 185.

51 Jenna Jordan, Leadership Decapitation: Strategic Targeting of Terrorist Organizations (Redwood City, CA: Stanford University Press, 2019), 3.

52 Jordan, Leadership Decapitation, 7–8.

53 Jordan, Leadership Decapitation, 7.

54 Jordan, Leadership Decapitation, 7.

55 Jordan, Leadership Decapitation, 8.

56 Jordan, Leadership Decapitation, 38.

57 Jordan, Leadership Decapitation, 63.

58 Jordan, Leadership Decapitation, 62.

59 Jordan, Leadership Decapitation, 67–68. Importantly, Jordan removes these nine groups from her statistical analysis in many models.

60 Jordan Leadership Decapitation, 66, Figure 4.5.

61 See, e.g., Michael C. Horowitz, “Nonstate Actors and the Diffusion of Innovations: The Case of Suicide Terrorism,” International Organization 64, no. 1 (2010): 33–64,; and Sidney G. Tarrow, Power in Movement: Social Movements and Contentious Politics (Cambridge, UK: Cambridge University Press, 2011), 192–93.

62 Jordan, Leadership Decapitation, 8–11.

63 Jordan, Leadership Decapitation, 9–10.

64 See, e.g., Robert W. McColl, “The Insurgent State: Territorial Bases of Revolution," Annals of the Association of American Geographers 59, no. 4 (1969): 613–31,

65 See, e.g., Megan A. Stewart, "Civil War as State-Making: Strategic Governance in Civil War," International Organization 72, no. 1 (Winter 2018): 205–26,

66 Petter Nesser, “Military Interventions, Jihadi Networks, and Terrorist Entrepreneurs: How the Islamic State Terror Wave Rose So High in Europe,” CTC Sentinel 12, no. 3 (March 2019),

67 Seth G. Jones, et al., Rolling Back the Islamic State, Rand Corporation, 2017, 20,

68 See, e.g., Jones et al., Rolling Back the Islamic State; Ahmed S. Hashim, “The Islamic State’s Way of War in Iraq and Syria: From Its Origins to the Post Caliphate Era,” Perspectives on Terrorism 13, no. 1 (February 2019): 22–31,; Mara Redlich Revkin, “What Explains Taxation by Resource-Rich Rebels? Evidence from the Islamic State in Syria,” Journal of Politics 82, no. 2 (April 2020),; and Thomas Maurer, “ISIS’s Warfare Functions: A Systematized Review of a Proto-State’s Conventional Conduct of Combat Operations,” Small Wars & Insurgencies 29, no. 2 (2018): 229–44,

69 Jordan, Leadership Decapitation, 11.