Leadership decapitation, which refers to the arrest or killing of a group's leadership, has become a key tool in current counterterrorism strategies This chapter presents an overview of the debate about leadership decapitation against terrorist organizations. Much of the optimism regarding the efficacy of decapitation as a counterterrorism strategy stems from the belief that terrorist groups depend upon the charisma of leaders for their cohesion. In order to understand whether decapitation works, this chapter presents three questions that will be answered in the book: (1) Under what conditions does leadership decapitation result in the decline of a terrorist organization? (2) Does leadership decapitation lengthen or shorten a group's life span? (3) In cases where decapitation does not result in a group's collapse, to what extent does it weaken a group and hinder its capacity to carry out attacks?

Chapter 2 develops a theory of organizational resilience that accounts for when decapitation is more or less likely to result in the decline or weakening of terrorist organizations. It argues that the efficacy of capturing or killing terrorist leaders is a function of three primary variables: the group's bureaucracy, communal support, and ideology. Bureaucratized organizations will have an easier time reorganizing after the loss of their leaders. Groups with significant levels of communal support should have access to resources that allow them to withstand attacks and continue carrying out their activities. Finally, religious and separatist groups are more likely to be based upon an ideological belief and doctrine that emerge from local communities and are not dependent upon the leadership for their rearticulation and continuation.

Chapter 3 introduces the dataset created for this study and explains the measures used to assess the efficacy of leadership targeting. It develops hypotheses to answer the following questions: Does decapitation result in organizational collapse? Does decapitation have an effect upon the occurrence and frequency of terrorist attacks? Does decapitation increase or shorten a group's life span? The following variables are examined to determine whether they are correlated with the efficacy of decapitation: position of a leader within the organization, the type of decapitation, organizational variables (size, age, or type), GDP, and regime type. Data on the survival rate of targeted and nontargeted groups is also analyzed to determine whether decapitation is an effective means by which to reduce organization's life span.

The chapter begins by looking at trends in leadership targeting. It then examines the impact of decapitation on organizational activity, organizational existence, attack frequency, and organizational survival. The data shows that organizational size, type, and leadership rank all have an impact on the probability that a group will experience a cessation of organizational activity after leadership decapitation. Large, religious, separatist, and Islamist groups are resilient to decapitation efforts and likely to continue carrying out activity. Targeting the top leader as opposed to members of the upper echelon is more likely to result in a cessation of activity, and groups in countries with a larger population are more likely to withstand leadership attacks. The chapter concludes with an overall assessment of the theoretical implications and policy recommendations regarding the efficacy of leadership targeting.

Chapter 5 examines Israeli attempts to capture or kill Hamas leaders from 1988 to 2014. It first looks at changes in the frequency and lethality of both conventional and suicide attacks in order to determine whether leadership targeting has affected Hamas's operational capacity. Hamas's bureaucratic hierarchy has increased its organizational stability and ability to withstand leadership attacks. The high degree of Palestinian support for Hamas has increased not only its strength and resilience to decapitation but also its legitimacy. The data shows that Palestinian support has increased over time, making Hamas even more resilient to leadership attacks. Finally, ideology is a critical factor. Hamas is both a separatist and a religious organization, which also plays a role in its ability to withstand repeated attacks on its leadership.

Chapter 6 explores the case of the Shining Path and accounts for variation in the outcome of targeting efforts. As the Shining Path became less bureaucratic in structure and experienced a loss in communal support, it became more susceptible to destabilization in the wake of leadership attacks. When Abimael Guzmán was arrested in 1992, the organization had a large amount of communal support and an organized bureaucratic authority structure. The ideology upon which the group relied was based on Guzmán's interpretation of Marxist thought. Given the group's high degree of institutionalization, its ideology became entrenched and was not dependent upon Guzmán. The organization was thus able to withstand the 1992 capture of Guzmán and other leaders. By 1999, when scar Ramírez Durand was arrested, the organization was already in a state of decline. It had lost a considerable number of its members and its bureaucratic structure was severely weakened.

Chapter 7 looks at the impact that decapitation attacks have had upon the operational capacity and organizational strength of al-Qaeda Central and al-Qaeda as a whole.

The book concludes with a discussion of the overall findings and theoretical arguments regarding the efficacy of leadership targeting. It then examines 198 instances of targeting efforts against ISIS leaders. The theory suggests that targeting is not likely to result in the demise or even a significant weakening of ISIS. It is an Islamist organization, bureaucratized, and with considerable amounts of communal support, albeit decentralized and in many cases coerced. Even if Abu Bakr al-Baghdadi is captured or killed and the organization undergoes a brief period of disruption, given the group's hierarchy of authority and chain of command, it should ultimately choose a successor easily and recover quickly. Furthermore, the statistical results regarding the resilience of large and Islamist organization is consistent with ISIS's resilience. The chapter concludes with policy recommendations regarding the use and impact of leadership decapitation as a counterterrorism policy.