Blogging on the New York Times website last April, New America Foundation senior fellow Robert Wright took issue with the Obama administration's decision to authorize the assassination of Anwar al-Awlaki, an American citizen identified by the U.S. government as a facilitator of the Al Qaeda terror network in Yemen. Aside from the legality of such an approach, wrote Wright, there's also the question of "whether assassinating terrorists really helps keep us safe. There's no way of answering this question with complete confidence, but it turns out that there are some relevant and little-known data."

The data Wright quoted came from "When Heads Roll: Assessing the Effectiveness of Leadership Decapitation," a paper published by political-science doctoral candidate Jenna Jordan, AM'03, in the journal Security Studies (Volume 18, Issue 4, 2009). Jordan notes in her introduction that, in the aftermath of 9/11, targeting the leaders of terrorist organizations has become a key feature of U.S. counterterrorism policy. To test the arguments made by academics and policy makers that a terrorist group can be dismantled by killing or arresting its leader, she examined 298 incidents of leadership targeting from 1945 through 2004, concluding that "decapitation is not an effective counterterrorism strategy" and that it oftentimes prolongs the life of a terrorist group. Jordan's findings have quickly reached a wide audience: soon after Wright's mention, several other prominent blogs and publications referenced her work and its possible implications for terrorism policy.

Jordan did not foresee becoming a terrorism researcher when she arrived at Chicago in 2001. Planning to specialize in international relations, she thought she might focus on examples of forced population transfers throughout history. But with Robert Pape, PhD'88, professor of political science and terrorism expert, as her adviser, and 9/11 occurring weeks before her matriculation, "it made sense that I fell into terrorism research." Searching for a master's thesis topic, Jordan consulted Pape and the two came up with the idea of looking at what happens to terrorist groups when their leaders are removed. She decided to build on that research for her dissertation, which she is finishing this fall while working as a research assistant to Harris School associate professor Ethan Bueno de Mesquita, AB'96.

The Security Studies article was adapted from Jordan's dissertation research. Looking at five variables—the age, size, and type of terrorist group; whether the targeted person was killed or arrested; and whether that person was the top leader or a notch below—she found that the characteristics that correlated most closely with the success of a decapitation were age, size, and type. As an organization becomes larger and older, it becomes more resilient to leadership removal. Religious groups such as Hamas are the most resistant to decapitation while ideological groups—i.e., those that are based on an ideology such as Marxism—are the most susceptible.

Jordan also found that decapitation was successful in only 17 percent of 298 cases and that even those groups would likely have disbanded faster without leadership decapitation. Using a pool of both terrorist organizations that had been decapitated and those that had not, she discovered that, overall, organizations that have not had their leaders removed are more apt to collapse than those that have—and that this is especially true for larger, older, and religious groups.

Within Jordan's model, an organization had to be inactive for two years following an attack on a leader to be coded as a success. To allow for richer analysis, Jordan also measured the extent to which decapitation results in organizational degradation (as opposed to complete inactivity or organizational collapse). Looking at three types of organizations—separatist (Basque Homeland and Freedom); religious (Hamas); and ideological (the Revolutionary Armed Forces of Colombia or FARC)—Jordan found that decapitation had little influence on FARC's ability to inflict damage but backfired in the religious and separatist organizations, causing an increased number of attacks or attacks that were more lethal.

"When Heads Roll" appeared in a special issue of Security Studies that focused on terrorism research and included an introduction by Pape. The issue came out in late 2009. About three months later, Wright's op-ed appeared. The writer called Jordan just before the piece was published: "He said, 'I'd like to reference your work and make sure that I'm not mischaracterizing it,' which I thought was really nice," she says. Wright's blog caught the attention of public policy and international relations bloggers: Matt Yglesias, a fellow at the Center for American Progress Action Fund and author of Heads in the Sand (Wiley, 2008); Juan R. I. Cole, a history professor at the University of Michigan; and Andrew Exum, a fellow at the Center for a New American Strategy. Both Yglesias's post and Exum's point to the chasm between current U.S. terrorism policy and Jordan's conclusions and urge policy makers and pundits to take note of her findings. Cole's blog expands on a fine-point distinction Jordan noted in her paper—between centralized and decentralized religious organizations, with the latter being far more common and resilient to decapitation. Several weeks after the blogs appeared, New York Times reporter Steven Lee Myers wrote in the paper's "Week in Review" section about the spring 2010 killings of two Al Qaeda leaders in Iraq, referencing Jordan's finding that smaller and younger organizations are easier to weaken via leadership targeting. The assassinations in Iraq might actually prove effective, argues Myers, since the Iraqi Al Qaeda franchise is only seven years young and shrinking.

Using the data presented in "When Heads Roll," Jordan has developed a theory of organizational resilience to explain why small, young, and ideological groups are easier to destabilize than those that are older, larger, and religious. She hypothesizes that older and larger groups should have developed bureaucratic features—such as administrative offices and hierarchies of authority—that increase group stability and facilitate a clear succession process. She also posits that religious groups would enjoy a high level of support from their surrounding community, affording access to critical resources. She uses two case studies to test her theory: the ideologically driven Peruvian organization Shining Path—which she is writing up this fall—and Hamas. Culling through historical documents and opinion polls, Jordan determined that as a large, 23-year-old, religious organization, Hamas is highly bureaucratic and benefits from high levels of community support—and that leadership decapitation has been ineffective within that organization, in fact causing an uptick in attacks. "Certain people have argued that Israel should continue targeting Hamas leaders and that it will eventually weaken the group significantly," says Jordan. "I make the argument that, actually, not only is it not effective, but that it has counterproductive consequences. It think that it emboldens groups and can increase sympathy for them—both local and international support."

For terrorism researchers, says Jordan, such arguments developed inside the academy are inextricably linked to the world outside it. "It's ideal to influence policy," she says. "If you believe in something, you have your work, and you stand behind it, it's wonderful if that research has relevance. So it was gratifying to see my work get picked up by the media—it would be even nicer if foreign policy were changing a bit."