How many causal paths lead to suicide terrorism?¹

Unfortunately, too many to produce precise predictions about when and where suicide terrorism is likely to occur. Nonetheless, Mia Bloom's, Diego Gambetta's, and Robert Pape's books do an excellent job of addressing this phenomenon with sophisticated theories and empirical findings. While Pape presents a coherent, single theoretical framework for explaining suicide terrorism, Bloom and the contributors in Gambetta's book focus on a range of loosely interconnected causal explanations across individual, organizational, and societal levels. These works also have a rich historical and comparative focus across time and cases. Even so, the fundamental question is how they advance our knowledge about suicide terrorism.

First, all three of these books direct our attention away from psychological and grievance-based explanations to strategic interactions among political groups. Bloom, Gambetta, and Pape eschew theories that rely on relative deprivation, humiliation, revenge, alienation, moral disengagement, and radicalization processes. They do not believe that there is a singular mentality or predisposition among suicide terrorists. Instead, they find that the roots of suicide terrorism are best found in the strategic calculations of political actors who strive for clear political objectives. Although these political actors vary substantially in terms of their goals, motives, capabilities, and organizations, they are nonetheless involved in a political struggle against much stronger adversaries. Thus, in order to explain why suicide terrorism occurs, Bloom, Pape, and Gambetta maintain that we need to start first by considering the relationships among groups who are contending for political power.

For Pape, the key relationships occur between democracies as foreign military occupiers and nationalist contenders who resist them. The bottom line is that suicide terrorism is a “strategy of national liberation” by local groups who aim to oust foreign military occupiers. Moreover, suicide terrorism is a more likely strategy when occupiers are democratic states, because challengers view them as “soft.” Basically, democracies are easy to coerce since even moderate amounts of damage that result from suicide attacks will gain media attention, increase domestic criticism and put pressure on their leaders to withdraw. Does the strategy work? Pape argues that it does, after finding that seven of 13 cases of suicide terrorist campaigns between 1980 and 2003 ended with significant policy concessions by democracies toward their adversaries. The most dramatic concessions involved American, French, and Israeli military withdrawals from Lebanon between 1983 and 1985 (Pape 2005, 40, 64).

While Pape focuses on the interactions between democracies and nationalist contenders, Bloom (2005) puts the spotlight on intragroup relationships, in particular interorganizational rivalry. As dissident organizations multiply and compete for recruits, reputation, and financial resources, their leaders rely more frequently on radical tactics in order to distinguish themselves from the pack and gain a greater share of the “protest pie.” As competition intensifies, groups escalate the destructiveness of their attacks in their efforts to outbid one another for limited resources and constituent support (Bloom 2005, 84–95).

In Making Sense of Suicide Missions (2005, 95–99), Luca Ricolfi's empirical analysis of Palestinian suicide attacks from 1981 to 2003 supports this argument. He finds that in the most recent wave, the al-Aqsa Intifada (2000–2003), the violence in the first months did not begin with suicide attacks, nor did it involve radical Palestinian groups such as Hamas or the Palestinian Islamic Jihad. Throughout the first five months of the uprising, the lion's share of violent attacks involved conventional strikes by secular al-Fatah organizations (e.g., Tanzim and Force-17), who tried to shore up their waning political support among the public. Shortly thereafter, Hamas and Palestinian Islamic Jihad commenced “martydom operations” with the aim of derailing secular forces from restoring their political dominance over the Palestinian public. In response, al-Fatah organizations jumped on the “suicide bandwagon” by launching the al-Aqsa Brigades, a new armed wing of the Palestinian Authority, whose main role was to organize and execute these operations. After three years of struggle and more than a hundred martyrdom operations, the Palestinian Authority was able to reconsolidate its political support until the 2006 national election when Hamas supplanted al-Fatah.

Another important political relationship to which all three works call attention is the link between dissident organizations and their public constituencies. Bloom, Gambetta, and Pape agree that local popular support determines the choices that dissidents make about when, where, and how suicide terrorism will be used. Pape (2005, 133–34) maintains that community support for martyrdom encourages individuals to become suicide terrorists. Because local communities honor them during holidays, name streets after them, post photographs of them on public buildings, and conduct public rallies on their behalf, dissidents volunteer for suicide missions, demonstrating their commitments to altruism and self-sacrifice.

Bloom (2005, 46), on the other hand, asserts that when violence resonates positively with the local populace, competitive outbidding between rival organizations will lead to more radical tactics, such as suicide terrorism. So, when do local populations become more favorably disposed to violence as a political solution? Bloom (p. 91) answers that in many cases, the state's counterinsurgency tactics designed to battle dissidents ratchet up public support. When counterterror policies produce extensive collateral deaths among civilians, local communities are more likely to endorse suicide terrorism that fails to discriminate between civilians and military targets. For instance, Bloom (pp. 93–94) points out that when the Russians and Israelis switched to more heavy-handed tactics, using aerial bombardments in Chechnya and helicopter gunships for assassination strikes among the Palestinians, these actions correlated significantly with both a rise in suicide terrorism and mass support for these missions among the general Chechen and Palestinian publics.

Meanwhile, Stathis Kalyvas and Ignacio Sánchez-Cuenca in Gambetta's Making Sense of Suicide Missions (2005, 221) hypothesize that the relationship between dissident organizations and popular support is U-shaped. At one extreme, organizations such as Hamas, Hezbollah, or the Tamil Tigers, which have widespread popular support within their communities, are better positioned to adopt radical policies. Hence, when supporters themselves are highly radicalized, organizations fail to experience “constituency costs” and are free to rely on suicide terrorism. In these instances, local populations are likely to be facing harsh and indiscriminant reprisals by incumbent governments. At the other extreme, organizations such as Al Qaeda and Palestinian Islamic Jihad are isolated, highly decentralized groups whose members engage in indiscriminate killings without any popular support whatsoever. In between these two poles reside intermediate cases (such as Euskadi ta Askatasuna [ETA] or the Irish Republican Army [IRA]) in which popular support is crucial but weak, which explains why these organizations are unlikely to rely on suicide terrorism. In short, the less constrained an organization is by its public supporters in terms of victim selection and modes of killing, the more likely it is to adopt suicide terrorism.

A second contribution that Bloom, Gambetta, and Pape make to the ongoing debate on suicide terrorism is their determination to locate its origins in the context of broader ongoing conflicts, such as civil war and rebellion. Of the three, Pape presents the most complete theoretical model linking rising nationalism, foreign occupation, and mass rebellion to suicide terrorism. He maintains that popular support for martyrdom operations increases when foreign military occupiers adhere to different religious beliefs from those of occupied communities. These religious differences fuel local ethnic insecurities about survival and the erosion of traditional rights and privileges, polarizing the social boundaries between the occupier and the occupied and increasing the opportunities for rebels to demonize their adversaries and to legitimize their use of suicide terrorism. In sum, religious difference is a key causal mechanism that encourages mass rebellion, facilitates the killing of noncombatants of an enemy community, and convinces individuals to kill themselves largely as an act of religious duty.

Along a similar but slightly different line of argument, Gambetta (2005, 290–92) hypothesizes that the interaction of civil war and religious difference is more likely to produce suicide terrorism when power asymmetries between the adversaries are especially high. More precisely, when the balance of military power is extremely lopsided (in favor of states over insurgents), religious allegiances are likely to generate a “bellicosity capital” that significantly increases the probability of suicide attacks and the willingness of insurgents to rely on them.²

However, in cases where civil wars are characterized by a lower asymmetry of power between adversaries who are also coreligionists, guerrilla war is more likely. Hence, Gambetta agrees that religious division in the context of civil wars is a key predictor for suicide terrorism, but the important causal mechanism is the uneven balance of power among the contenders when religious minorities are both more likely to be targeted and more likely to fight back.

In addition to the context of civil wars and rebellions, Bloom and Gambetta assert that suicide missions coexist with other repertoires of collective action that adversaries also employ against governments and their security forces. Guerrilla actions, assassinations, clashes, demonstrations, and riots are equally important tactics that challengers use, but these actions, even though they outnumber suicide attacks, are reported less frequently by the media, which are drawn to reporting more sensational events involving suicide attacks. So when does the opposition choose suicide terrorism over other tactics? Tactical adapation and innovation provide a partial answer.

Bloom (2005, 83) argues that insurgents weigh the relative effectiveness of various strategies, “learning” and “imitating” tactics that have worked in the past and “discarding” those that the opposition has countered or adapted to successfully. She reminds us that challengers usually choose suicide terrorism after their initial strategies have been ineffective in achieving their political goals.³

For instance, she notes that suicide attacks have appeared more frequently in the second iteration of rebellions by the Palestinians, Chechens, and Kurds. Similarly, in his analysis of Palestinian behavior between 1981 and 2003, Ricolfi (Gambetta 2005, 102–3) finds that the shift from air hijackings in the 1960s and 1970s to suicide missions in the 1980s and 1990s reflects a technological leap toward greater efficiency in achieving desirable outcomes. Initially, air hijackings were successful in bringing the Palestinian cause to the attention of the international community, generating widespread recognition of the Palestine Liberation Organization. By the end of the 1970s, these hijackings produced more criticism than support for the Palestinians and increased the necessity for newer actions that were more efficient in terms of inflicting damage, sustaining Palestinian morale, and maintaining international attention on the Palestinian cause.

From a more evolutionary perspective, Gambetta asserts that we should understand suicide terrorism in terms of both its historical lineage and its diffusion across insurgencies. He explains (2005, 287) that suicide missions reached Lebanon in the 1980s largely as a result of both the 15-year-long civil war, which radicalized local groups, and the emigration of Iranian revolutionaries who moved there to establish a “beachhead for the Islamic Revolution.” These Iranian émigrés mobilized the local Shiite community, founded Hezbollah, and launched martydom operations against Israeli military targets in Lebanon. Rapidly, suicide terrorism spread to Sri Lanka, Israel, Turkey, and Kashmir in the 1990s, in 2000 to Chechnya and the Occupied Territories and in 2003 to Iraq. The “Hezbollah mutation” also spread from Shiite to Sunni Muslims and eventually to secular groups as well. Over time, suicide terrorism has diffused and changed globally, but its origins are located in Lebanon between 1973 and 1986 where nationalist, religious and ethnic cleavages mixed with civil war and a failing state.

Finally, the works of Bloom, Gambetta, and Pape are significant because together they present a causal picture that is governed by “equifinality,” rather than “homogeneity.” In other words, there are many causal paths to suicide terrorism. Although these authors agree that strategic calculations influence the choice for terrorism, they acknowledge that there are diverse goals and complex causal processes that are likely to vary in the contexts of civil war and rebellion. For example, Ricolfi (in Gambetta, 84–97) finds that four waves of Palestinian suicide terrorism dominated the Middle East landscape from 1981 to 2002. The first campaign occurred in Lebanon (1981–85), the second during the First Intifada (1988–90), the third in the aftermath of the Oslo Accords (1994–96), and the last during the al-Aqsa Intifada (2001–2). Although these waves are part of the same Israeli-Palestinian conflict, Ricolfi finds that each one occurred for different reasons that are largely related to changes in constraints and resources available to dissident organizations. In addition, the characteristics of the suicide missions themselves varied in terms of locations, organizations, women participants, political objectives, and finally, the frequency and lethality of the attacks. Therefore, it makes sense that we avoid unitary or generic explanations in favor of those that explain why suicide terrorism occurs in certain periods and places and not in others. This effort does not mean that we should resort to idiosyncratic or imprecise approaches, but it does mean that theorizing about suicide terrorism is going to be complex, messy, and unlikely to produce simple or clear predictions.

In light of these contributions, the works of Bloom, Gambetta, and Pape have deepened our theoretical approaches to suicide terrorism. Yet these works neglect two important issues. The first one involves an underestimation of how states as actors are inextricably linked to tactical choices that result in suicide terrorism. That is not to say that these authors fail to recognize that when states apply counterinsurgency policies that do not discriminate between civilians and terrorists, their actions actually increase public support and volunteers for suicide missions. The more fundamental problem is that they overlook the relational aspects of suicide terrorism; that is, suicide attacks occur in the context of two-way interactions between states and dissidents. This oversight is troubling when we consider that over 80% of the cases of suicide terrorism in the world between 1981 and 2003 have occurred in the Israeli-Palestinian and Sri Lanka areas where states face intense direct opposition to their policies (Ricolfi in Gambetta, 81).

If Bloom, Gambetta, and Pape all agree that suicide terrorism is one component of terrorist organizations' repertoire of collective action, then more effort should be devoted to investigating how states' policies affect the tactical policies of these organizations and vice versa. Why not consider that the mixes of actions emitted between states and terrorist organizations evolve or change over time and that the action sets of these actors coevolve with each other (Oliver and Myers 2003, 1)? Pamela Oliver and Daniel Myers's work on coevolutionary processes suggests that terrorist organizations learn over time from their past interactions and from information communicated to them through other actors. Meanwhile, new opposition tactics diffuse through opposition networks, and new regime responses diffuse through new regime networks. These new forms of actions and counteractions influence the course of subsequent interactions between terrorist organizations and states (Oliver and Myers, p. 3).

Zeev Maoz's (2004) analysis of Israel's use of limited military force against Palestinians during the al-Aqsa Intifada between 2001 and 2003 illustrates the significance of systematically investigating the two-way relationship between states and their oppositions. Maoz (pp. 15, 17, 30) maintains that during Prime Minister Ariel Sharon's administration, Israel embarked on a military strategy on four separate occasions that involved the use of assassination strikes against Palestinian leaders for the purpose of provoking Palestinian retaliatory strikes in the form of suicide bombings. Israel would then use the suicide bombings as a pretext for launching a more sustained military operation in the Occupied Territories for the purpose of destroying public infrastructures that were perceived to be producing the materials and explosives for suicide bombings.⁴

Thus, Maoz's analysis reinforces the necessity of studying suicide terrorism not as an isolated phenomenon but in terms of a strategic interplay between states and their oppositions.

The second issue is the tendency of these authors to underplay the human costs of occupation and repression that encourage individuals to participate in suicide missions. For instance, Pape (2005, 58) maintains that suicide terrorism is not a product of the severity of the occupier's policies, because he finds no correlation between the number of deaths in an occupied community and its number of suicide terrorists aggregated over nine regional cases of foreign occupation between 1982 and 2003. Yet other scholars have found a direct relationship between repressive occupation policies and radicalism. Sean Yom and Basel Saleh (2004, 24) discovered that a significant number of Palestinian suicide bombers have either been arrested or have experienced the death or injury of a family member by the Israeli Defense Forces prior to volunteering for a suicide mission. This pattern also correlates with Robert White's (1989) findings elicited from interviews of IRA supporters in 1987. He found that activists joined the IRA and embraced violent tactics largely because of British repression (e.g., internments, arrests, home invasions, and deaths), especially those policies that adversely affected close personal friends or family members. Essentially, British occupation policies introduced new grievances in addition to long-term historical grievances and consequently accelerated the radicalization process within activists. So the bottom line here is that we should be wary of discarding the connections among repression, grievances, and radicalization processes too quickly.

Despite these weaknesses, Bloom, Gambetta, and Pape make some important policy recommendations about how states should handle terrorist organizations and their networks. The most obvious one is that states should pursue terrorists through carefully selected policies that avoid residual damage to civilians who reside in communities that have the potential to provide important support to terrorist organizations. In this case, policies that target terrorists for assassination are not necessarily productive. These actions inevitably result in civilian causalities that increase grievances, but they also serve the interests of terrorists who create “national myths, martyrs and cults of personality.” Equally important, targeted killings make it harder for moderates in the opposition to contain or marginalize the radicals because they lose credibility within their general public (Bloom, p. 100).⁵

In contrast, states that apply policies that distinguish between moderate and radical groups are more likely to be effective in reducing terrorism. Bloom (pp. 98–99) refers to this as a strategy of “outbidding the outbidders”; that is, states extend economic development programs and/or the promise of a negotiated settlement with the aim of giving communities a stake in a peace process that offers the hope of future prosperity and stability. Such a plan fragments the opposition between moderates and radicals, thereby isolating the radicals and their networks and easing the way for states to identify and remove them. It is especially successful if states have been able to dismantle their external sources of financial support, making terrorists more dependent on local sources of support (p. 100).

In conclusion, Bloom, Gambetta, and Pape have shifted the discussion of suicide terrorism to a more sophisticated theoretical level and beyond the impressionistic and descriptive work that tends to dominate this literature. Their works reflect a strong commitment to complex explanations that involve multiple levels of analysis and numerous causal mechanisms. They also imply important policy suggestions about what states should or should not do in order to contain suicide terrorism in the long run.