There are two important questions to consider in studying suicide terrorism. First, why has suicide terrorism emerged in the last few decades as such a potent weapon? Second, why is it that some terrorist groups use suicide terrorism, while others have not? Suicide terrorism has emerged as a very powerful weapon over the last several years, with 9/11, car bombings in Iraq, in the West Bank, in Sri Lanka and elsewhere. It has captivated the public. As a tactic, it has infiltrated our national consciousness. However, we need to stop viewing suicide terrorism as something exotic and incomprehensible, which only leads to confusion. It makes more sense to think of it as an example of a military innovation for non-state actors and to apply some of the analytical tools we use to analyze the spread, or diffusion, of nuclear weapons, carrier warfare, or blitzkrieg warfare.

Many argue that suicide terrorism is more effective than other kinds of terrorist attacks. In Dying to Win: The Strategic Logic of Suicide Terrorism (2005), Robert Pape of the University of Chicago found that, excluding 9/11, from 1980-2003, suicide attacks represented 3 percent of all terrorist incidents, but 48 percent of the casualties. This means that the bang for the buck in the average suicide attack is extraordinarily high. However, we tend to view suicide terrorism as something simple for those who do it—you strap a bomb on and blow yourself up, or you get in a car that has a bomb and run it into something. In fact, there is a complicated organizational challenge associated with adopting suicide terrorism. It is not a costless move for terrorist organizations. Some of the difficulties involved in adopting suicide terrorism explain why, while some groups have chosen to use it, others have not. In particular, suicide terrorism proved exceptionally difficult to adopt for the most successful terrorist groups of the pre-suicide bombing era. Like successful businesses that fail to adapt in a changing strategic environment because they were too stuck in their old routines and ways of operating, the PLO, the Provisional IRA, and the Basque ETA all failed to adopt in the short to medium term. Only the PLO’s Fatah, of the three, ever adopted it, and that was almost two decades after the introduction of the innovation.

In addition to looking at the organizational decision to use suicide bombing, we should also focus on suicide terrorism as an example of the diffusion of innovations. One brief story with repercussions for U.S. national security illustrates the interconnections among groups and the importance of understanding how they operate. In the early 1990s, when Osama bin Laden was shifting Al Qaeda into more of a direct operational role, he needed to figure out the best way to attack an American embassy. He looked at different plans and ideas other groups had had. He recalled Hezbollah’s bombing of the U.S. Marines barracks in 1983 and Hezbollah’s other successes with suicide bombings. So, despite profound theological differences between the Salafist/jihadist views of Al Qaeda and the Shiite Hezbollah, Bin Laden sent his operatives to go talk to the Hezbollah leadership. They came back with what were effectively operational blueprints for how to plan and executive suicide attacks, especially against hard targets like embassies. The East African embassy attacks resulted in part from this example of diffusion. In the 1980s, Hezbollah was really thought of as an innovator, the first mover. This story shows the spread of the idea to the primary adopter of suicide terrorism in the 1990s and beyond—Al Qaeda. The subsequent history of suicide terrorism is best thought about as a diffusion process.

Defining Suicide Terrorism

It is very difficult to define terrorism in general. Even parts of the U.S. government cannot agree on a definition. Suicide terrorism is easier to understand conceptually. It is a violent attack designed to kill others where the death of the attacker is a necessary part of the action. This is different from a suicide mission. In WWII movies, you have the suicide mission where the men get together and are sent on a mission that they know they will not survive. The means of destruction in this case, the way they perpetrate the attack, is the machinegun they fire, the grenade they throw, or the bomb they drop. They know they are probably going to die, but it is not their deaths that cause the mission to succeed. They are simply going to die accomplishing their mission. That is very different than a suicide attack where it is through your death that your mission, the killing of others or destruction of a target, is accomplished. The mission is accomplished through your death.

We all know about imperial Japan’s use of kamikaze tactics at the end of WWII. In mid-1944, in response to growing Japanese losses and especially the large decline in the quality of Japanese pilots, the Japanese turned to using the planes as weapons themselves, flying them directly into U.S. ships. Historians disagree about when exactly this debuted, but most would cite Leyte Gulf in October 1944 as the first place we saw it en masse. By the end of the war, the Japanese had sunk between about 34 and 70 ships and killed thousands of Allied soldiers through this tactic. Most military historians do not consider Japan’s efforts a success, one reason being that to accomplish this, the Japanese sacrificed almost 5,000 pilots. But this is a clear example of the use of suicide attacks.

The Modern Era

Suicide bombings disappeared until the early 1980s, the beginning of the suicide terrorism era in Lebanon. In 1982, radical elements of the Shiite resistance in southern Lebanon joined together in the Bekka Valley to form Hezbollah. The group was aided by Iranian Revolutionary Guards, who may have brought with them Iranian human wave tactics from the Iran-Iraq war. While not the first suicide attack in the period—that occurred in 1981—the first known attack by Hezbollah was on November 11, 1982, against an Israeli military installation. The success of that attack prompted Hezbollah to continue, which led to the worst terrorist attack overseas against U.S. assets, the Marine barracks bombing that killed over 200 Americans.

The way Hezbollah thought about the attacks highlights basic questions about motivations that analysts continue to discuss today. According to Martin Kramer, when Hezbollah considered whether to continue suicide bombings, the decision was in part a theological decision driven by practical concerns. Clerics justified suicide bombings for two reasons: the genuine devotion of the martyr and the practical utility of the attack. As the spiritual leader of Hezbollah, Sayyid Muhammad Husayn Fadlallah, said, “the Muslims believe that you struggle by transforming yourself into a living bomb like you struggle with a gun in your hand. There is no difference between dying with a gun in your hand or exploding yourself.” (Kramer 1991) However, note the practical element of the justification as well. Later in the 1980s, when Hezbollah’s leaders decided the attacks were not achieving the same successes as before, either tactically or strategically, it made sense to stop. This shows, at an early point, the interconnectedness between religious and practical arguments for suicide bombing.

The perceived success of the tactic and the notoriety Hezbollah had gained led to the spread of suicide bombing. The Tamil Tigers in Sri Lanka became a non-Muslim and non-Middle Eastern early adopter in 1987. The Tamil Tigers came out of a resistance movement in Sri Lanka that sought independence and autonomy. In 1987 they began a suicide campaign that spanned multiple decades. Before 9/11 and the ensuing spate of suicide bombings in places like Afghanistan and Iraq, the Tamil Tigers were actually the most prolific adopter of suicide terrorism in the world, credited with over 150 attacks; 191 is one estimate.

The LTTE is very interesting from a targeting perspective. We tend to conceptualize suicide terrorism as being about attacking civilians. While Hezbollah did not necessarily focus on attacking civilians, groups like Hamas or Al Qaeda (and affiliates) have caused the association of suicide bombings with civilian targeting. Alternatively, the LTTE, especially at the outset, conceptualized suicide attacks very differently. They used suicide bombing more as a substitute for military operations they could not complete with conventional means, making them asymmetric but closer to the traditional military sense of the term. The Tamils thought about suicide bombing more for hard targets and assassinations, not necessarily targeting civilians, though civilians often died in their attacks.

Theories for Rise of Suicide Terrorism

Suicide campaigns increased steadily from the early 1980s to 2001 and beyond. The number of suicide attacks worldwide between 2001 and 2005 shows a more than secular increase in the number of attacks. Why? One explanation revolves around individual-level factors—individuals who had grievances against a government or group who sought to demonstrate their anger or fury through a suicide attack. Other explanations postulated psychological weaknesses or proclivity to suicide. Few scholars still accept those sorts of arguments. Research by Alan Krueger and others seems to suggest there is not a strong link between economic weakness and suicide terrorism, either at the national or individual level. Two recent theories, however, have met with some acceptance.

One, by Robert Pape, has to do with occupation. He finds that when groups are or feel occupied, they are much more likely to resort to a tactic like suicide terrorism. Pape’s argument has intuitive appeal given the actions of a group like Hamas, which feels occupied so arguably turned to suicide terrorism to make a splash, get media attention, and try to demonstrate to their occupier, Israel, the true cost of their actions. However, one problem with Pape’s argument is that many occupied groups have not used suicide terrorism. Consider the Provisional Irish Republican Army (IRA) in Northern Ireland, a violent terrorist group whose members had no problem dying for the cause but which never adopted suicide terrorism (on a few occasions they kidnapped families and forced the husband to drive a bomb loaded with explosives towards a checkpoint, but those are coercive rather than voluntary). So, while occupation can explain some cases of suicide bombing, it cannot explain non-adoption by prominent groups.

Another explanation, by Mia Bloom of the University of Georgia, has to do with what she calls “outbidding.” Bloom held in Dying to Kill: The Allure of Suicide Terror (2005) that if you want to understand suicide terrorism, you have to understand the competition for control that often happens in insurgency situations. Multiple groups committed to a cause try to demonstrate their commitment to the broader public, and there is no better way to do that than to show the absolute willingness of group members to give up their lives for the cause. If the public is supportive, the competition proves which groups “legitimately” represents the interests of its people. This drives the escalation to suicide terrorism. While parts of the outbidding explanation are persuasive, one problem is that while it actually does a reasonable job of explaining some of the behavior in the Palestinian territories, it does not explain suicide campaigns where there are not elite competitions for control. For example, in the Tamil case, the struggle for influence among Tamil resistance groups was over before the Tamil Tigers’ suicide terror campaign began.

A third theory has to do with the combination of religion and globalization. In The Globalization of Martyrdom: Al Qaeda, Salafi Jihad, and the Diffusion of Suicide Attacks (Johns Hopkins University Press, forthcoming November 2008), Assaf Moghadam of the Combating Terrorism Center at West Point argues that the increase in suicide terrorism over time is really driven by the Salafists/jihadists. So most important is understanding Al Qaeda and the globalization of terrorism. Moghadam’s work is part of an interesting new wave of suicide terrorism research.

Explaining suicide terrorism requires viewing it as a military innovation and better understanding the organizational requirements needed for its adoption. The Provisional IRA was a non-adopter of suicide terrorism despite being one of the most successful terrorist groups of the 1970s and 1980s. It had complicated training manuals and almost a mini-state-like bureaucracy. It focused first and foremost on the survival of their volunteers, the term they used for group members. How do you square that with something like suicide terrorism? Organizational theorists like James Q. Wilson have identified something called “critical task focus,” which refers to the way an organization defines its goals and objectives. The Provisional IRA’s focus on the survival of its volunteers as part of its goal led to the conflation of its critical task focus with the way it conducted its operations, confusing means and ends. Since the group built into its reason for existing the survival of its members, how do you tell them to go kill themselves?

Another way to think about organizational requirements has to do with experimentation and organizational age. Economist Mancur Olson argues that as countries and bureaucracies age, they develop more and more sub-layers and veto points. People gain prestige, privilege, and get promoted in an organization on the basis of their talent, somewhat like in a business. As specialization captures an organization and it develops more extensive bureaucratic layering, it becomes much harder for the organization to change what it is doing if it turns out that it should do something different. So, what do you do with a terror group that has built up expertise in something like remote bombing or attacking military bases? For those groups, adoption of suicide terrorism is very difficult because they are embedded in the ways they have always done business.

Cost generally does not govern whether or not a group is going to adopt suicide terrorism. A suicide terrorism attack costs only about $150, so money is not the obstacle. The organizational element is the real obstacle. Therefore, which groups should be more likely to adopt and which should be more likely to pass on suicide bombing even if that tactic, on the surface, could help them achieve their goals? It should be easier for the younger groups that do not have embedded ways of doing business to adopt suicide terrorism and harder for those more established groups.

How do we test this idea? I studied over 800 terrorist groups from 1968 onwards, the universe of terrorist groups during that period according to the Memorial Institute for the Prevention of Terrorism, looking at whether or not they used suicide terrorism. Using statistical analysis to control for numerous factors, such as whether a group was affiliated with Al Qaeda, whether it was involved in the Arab-Israeli conflict, or whether the group felt it was occupied, I assessed whether the probability that a group will adopt suicide terrorism relates to how long the group has existed, or its organizational age. The results strongly support the idea that there is something about organizational dynamics that helps drive the suicide bombing process. For groups that are religiously affiliated, who claim the reason they exist has something to do with their religious beliefs, the probability of adoption is very high at the beginning. Groups that have more established ways of doing business are significantly less likely to adopt.

A good example of these dynamics comes from Fatah, Yasser Arafat’s organization in the Palestinian Territories. They eventually adopted suicide terrorism in 2000 in the Second Intifada, years after Hamas and Islamic Jihad. One explanation for their delay is the way prestige was locked up with particular people and within the organization. You received credit and priority in the organization based on hijackings, kidnappings, and remote attacks. It made suicide terrorism something very complicated for them to deal with organizationally. It took them a long time to figure out how to adopt it.

For non-religiously motivated groups, how long they exist does not have as strong an affect on the probability of adopting suicide terrorism. Looking at all known suicide terrorism groups from 1983 to 2006, we see many direct connections (for instance, we know that Hamas and Hezbollah talked about suicide terrorism after the expulsion of Hamas members from Israel to southern Lebanon in 1992) and also indirect connections (the Tamil Tigers/LTTE invented the suicide vest, which Middle Eastern groups like Hamas and others then modeled). Adding together the direct and indirect links among groups, almost every suicide terrorism adopter is linked together in one way or another. In the 1980s, Hezbollah was the hub from which suicide tactics spread to the Palestinians and other groups. In the 1990s and beyond, Al Qaeda became the hub. When analysts used to study suicide terrorism, they tended to ask, “Why did Hamas do it? Why did the Taliban do it?” Rather than focusing just on individual groups, the phenomenon is best understood as part of a diffusion process.

Over the last few years, Afghanistan and Iraq have become the centers of suicide bombing activity. From March 2003 to February 2006, between former Baathist ideologues and Zarqawi and Al Qaeda in Iraq, there were more than 400 suicide attacks against U.S.-led forces, Iraqi civilians, and other groups. In the past year, the Anbar awakening and the surge have been fairly successful at decreasing the number of all types of attacks against U.S. troops, but the number of suicide attacks has stayed the same or even increased. The month-by-month numbers show spikes in relation to important events such as Fallujah, so it is possible that this divergence, where total attacks decline but suicide attacks stay the same, shows that the decision to engage in suicide attacks is different than the decision to engage in attacks in general or that suicide attacks are simply much harder to stop.

Suicide terrorism in general has become more normalized over the last decade. Bloom recently presented a paper at the annual meeting of the International Studies Association on this point. She has noticed a normalization and regularization in the past couple of years. While it began as something unique, suicide terrorism is now a regular tool of sectarian violence. It is therefore unlikely that we will see suicide bombing go away. We see this both in Afghanistan and with the increasing use of female suicide bombers.

Conclusion

Despite the historical roots of suicide terrorism with the kamikazes in WWII, the tactic never really caught on with states. Nation-states generally have more efficient ways to produce the same amount of force than suicide attacks. The era of suicide terrorism really began in Lebanon in the early 1980s. We can best make sense of it if we think of it as a military innovation, not as something exotic, and if we study it from a diffusion perspective. Instead of wondering why a group is doing this grotesque thing, we need to wonder why they are but others are not. The evidence suggests the importance of organizational factors in driving the adoption or non-adoption of suicide terrorism, as well as the existence of a diffusion process where the innovation spreads among groups. Therefore, we should study suicide terrorism in a serious fashion, looking at the big picture and the key variables that explain behavior, rather than in an emotional manner.