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Terror's Measure

Since 9/11, researchers have produced a large number of studies of terrorism – analyses that help provide a basis for understanding the nature of the threat. 

Since Sept. 11, 2001, numerous reports and studies have been released by a variety of institutes and organizations, in and out of the government, about American domestic terrorism, most often with a focus on homegrown jihadists. Other reports have taken into consideration the rise of domestic right-wing terrorism, especially since the 1990s, and attempted to include these incidents and individuals in their datasets. What many studies on domestic terrorism since 9/11 indicate is that although there have been homegrown jihadist plots and attacks, this threat has been overblown in the media, which leads to incorrect assumptions about American Muslims in general and may have contributed to a rise in anti-Muslim sentiment. Nor, as one analysis says, does the media report on the extensive and visible work Muslim-American communities have done in regularly speaking out against violence, organizing against it, and confronting Islamic radicalization.

The reports make a number of interesting points. Most tips to law enforcement about homegrown jihadists come from American Muslim communities, one said. Another focused on the fact that not all Muslims in this country come from Middle Eastern countries — a number involved in domestic terrorist plots are black, white or Latino citizens who converted to Islam. Overall, the studies seem to indicate that homegrown jihadist terrorism has been significantly less deadly than other forms of domestic terrorism, in particular that from the radical right. Indeed, several of them find that right-wing terrorism is a very serious threat. A 2005 report from the FBI, in fact, concludes that terror from the right is the most dangerous and prolific.

The studies come with their own sets of problems, however, and have to be used with caution. Mark Pitcavage, director of fact-finding for the Anti-Defamation League, a Jewish civil rights organization, puts it like this: “Studies on the state of various extremist or terrorist movements can often be quite useful in increasing knowledge and awareness for the general public, or specific audiences such as law enforcement. So can studies on emerging trends within such movements. Such projects, though, must be used carefully. Reliable quantitative data on extremist-related subjects is very difficult to come by and some studies have used datasets that are incomplete or otherwise flawed. Moreover, a few studies have been conducted by researchers without nuanced knowledge and understanding of the extremist movements they have examined, which can result in flawed analysis. Critical assessment is key to getting value out of extremist-related studies.”

One of the reasons that it’s difficult to define and count incidents of right-wing terrorism is that many right-wing extremists involved in incidents of terrorism are not prosecuted under terrorism statutes, but rather under other state and federal laws such as those governing weapons. There are also misunderstandings about what qualifies as terrorism, especially since the Department of Justice and the FBI do not publicly list domestic organizations involved in terrorism or terrorist plots, nor does any U.S. governmental agency release lists of terrorist incidents (although the State Department does compile a list of foreign groups judged to be terrorist). The United States might do well to take a lesson from overseas. Each year, Europol, the European Union’s law enforcement agency, publishes a report on terrorism meant to aid law enforcement officials and policymakers as well as to inform the general public. European nations including the Czech Republic, Germany, the Netherlands, Norway, Sweden and the United Kingdom also publish their own annual reports.

What follows are brief summaries of recent studies, organized in reverse chronological order (and, within years, alphabetically, according to the lead author’s surname), that may help readers understand terrorism in America today.

Many Paths to Muslim Radicalization

Jerome P. Bjelopera, “American Jihadist Terrorism: Combating a Complex Threat,” Congressional Research Service, 2013

This study from the nonpartisan Congressional Research Service defines what a “home-grown” jihadist terrorist is (terrorist activity or plots perpetrated within the U.S. or abroad by American citizens, legal permanent residents, or visitors who have been radicalized primarily within the U.S.) and provides an analysis of the phenomenon and an appendix listing 63 plots since 9/11. It says that radicalization can occur in the U.S. through the Internet, social networks, intermediaries and, to a lesser extent, prison, and emphasizes the difficulties in categorizing homegrown violent jihadist activity, since no “workable general profile of domestic violent jihadists exists.” The author makes recommendations to combat the threat, such as developing closer relationships between law enforcement officials and American Muslim communities. He also notes an uptick in activity after 2009, but suggests that only a “tiny minority” of Americans is susceptible to jihadist ideologies.

Jihadism Less Deadly Since 9/11

Peter Bergen, “The Homegrown Threat: Right- and Left-Wing Terrorism Since 9/11,” New American Foundation and Syracuse University’s Maxwell School of Public Policy, 2012

Bergen examined cases of jihadist and non-jihadist terrorism in the United States between 9/11 and December 2012. His study concludes that Islamist terrorism since the catastrophic attacks of 2001 (when nearly 3,000 Americans were killed) has been less deadly in the U.S. than other forms and that Muslims are just as likely as non-Muslims to report possible extremism to authorities. It notes that 380 people were indicted on terrorism-related charges during the period, and, of those, 207 were jihadist and 174 were non-jihadist. In the latter category, the overwhelming majority (80%) were right-wing extremists. Since 9/11, at least 29 people have been killed by non-jihadist extremists while 17 have died at the hands of jihadists, the study concludes. The study includes an extensive list of terrorist incidents, which can be searched and sorted at the New America Foundation website (

Domestic Extremism on the Rise

Jerome P. Bjelopera, “The Domestic Terrorist Threat: Background and Issues for Congress,” Congressional Research Service, 2012

This study provides an overview of domestic extremist ideologies, both right- and left-wing (including antigovernment, animal rights and white supremacist activists) and exhorts Congress and counterterrorism policymakers to take these threats as seriously as jihadist terrorism. It says that domestic non-jihadist terrorists have been responsible for over two dozen incidents since 9/11 and that there has been a growth in antigovernment extremist activity in recent years, but notes difficulties in defining the scope of domestic terrorism due to the fact that federal agencies employ varying terminologies and definitions. The study also notes that there is a lack of uniformity in how domestic terrorists are prosecuted and that government agencies tend to define “threats” rather than “groups,” and it adds that it’s unclear how those agencies arrived at that list. The report does not include a list of incidents or individuals.

U.S. Far Right Grows More Violent

Arie Perliger, “Challengers from the Sidelines: Understanding America’s Violent Far-Right,” Combating Terrorism Center at West Point, 2012

Perliger’s study provides an extensive social and historical overview of the different ideologies and history of U.S. far-right groups and notes the rise of far-right violence in the 1990s. In a potentially controversial finding, Perliger asserts that the 2000s experienced four times the level of far-right violence than the 1990s did. The study defines three ideologies within the far right, including a racist/white supremacist movement, an anti-federalist movement, and a fundamentalist religious movement. It also provides an analysis of trends in far-right violence using a dataset constructed solely for the study that includes 4,420 violent incidents that occurred between 1990 and 2012 within U.S. borders. It links spikes in far-right violence to larger political and judicial currents, including anti-segregation legislation, the 1964 Civil Rights Act, a series of abortion-related Supreme Court decisions in the late 1980s and early 1990s, and anti-gun legislation in the early 1990s. It also includes an overview of far-right violence by state, and an analysis of contributing factors. The top five states, according to the study, are California, Florida, Illinois, New York and Texas.

U.S. Muslim Extremism Not Rising

Alejandro J. Beutel, “Data on Post-9/11 Terrorism in the United States,” Muslim Public Affairs Council Policy Report, 2011

This study offers a statistical analysis of convictions in terrorism trials in the United States since 9/11 and an analysis of the Muslim Public Affairs Council’s post-9/11 Terrorism Incident Database, a list drawn from government, conservative and progressive sources. That database includes Muslim and non-Muslim violent extremists and includes those who originate inside and outside the U.S., but it is limited to plots specifically against people. The study concludes that there has been a general rise in violent extremism across ideologies since 9/11, but argues that there is little evidence of rising ideological extremism among Muslim Americans. According to the MPAC dataset, there have been 93 plots against the U.S. by U.S.-originated non-Muslims since 9/11, compared to 46 plots from U.S.- and foreign-originated Muslims. The study found that American Muslims helped prevent more than two out of every five Al Qaeda plots that have threatened the U.S. since 9/11.

Hate Groups in America Often Violent

Steven M. Chermak, Joshua D. Freilich and Michael Suttmoeller, “The Organizational Dynamics of Far-Right Hate Groups in the United States: Comparing Violent to Non-Violent Organizations,” National Consortium for the Study of Terrorism and Responses to Terrorism, Department of Homeland Security, 2011

Carried out by scholars for the Department of Homeland Security, this study finds that far-right American hate groups pose a “significant threat to public safety” and, based on the Extremist Crime Database, concludes that domestic far-right extremists have been involved in at least 330 homicide events that have claimed over 560 lives from 1990 to 2010. It also found that far-right extremists were linked to 60 planned and/or attempted terrorist plots between 1995 and 2005. The researchers used data from the Southern Poverty Law Center to create a sample of 275 far-right hate groups and developed an analysis of factors that it said help determine whether a domestic hate group or its members are likely to engage in violence.

Al Qaeda Recruitment in U.S. Low

Brian Michael Jenkins, “Stray Dogs and Virtual Armies: Radicalization and Recruitment to Jihadist Terrorism in the United States Since 9/11,” RAND Corporation, 2011

This RAND Corporation study analyzes how effective Al Qaeda has been at recruiting homegrown terrorists in the U.S. and concludes that, so far, the number has been relatively small: 176 individuals arrested, indicted, or identified as jihadist terrorists or supporters since 9/11 out of a total population of several million American Muslims. The vast majority of America’s Muslim immigrants, Jenkins finds, have assimilated into American society and overwhelmingly reject jihadist ideology. The study states that, overall, Somalis and Pakistanis are “heavily represented” among America’s homegrown jihadists. Jenkins also suggests that Muslim diaspora communities in the U.S. that have links to war zones and are struggling with assimilation may be the most likely to produce homegrown terrorists. He recommends that law enforcement work closely with communities from which terrorists may emerge, providing assistance in assimilation, earning trust, and preventing discrimination. The study argues that needless alarm and exaggerated portrayals of the Muslim terrorist threat actually encourage terrorism, as do unrealistic expectations of a risk-free society and unreasonable demands for absolute protection. It includes a chronology of jihadist terror cases since 2002.

U.S. Muslim Terror Down Since 9/11

Charles Kurzman, “Muslim-American Terrorism Since 9/11: An Accounting,” University of North Carolina: Triangle Center on Terrorism and Homeland Security, 2011

Kurzman’s study aims to answer the question of whether Muslim Americans truly are “turning to terrorism.” His most remarkable finding is that of 120 Muslims suspected of plotting terror attacks in the U.S. since 9/11, 48 were uncovered through tips to authorities from fellow Muslims. Since 9/11, according to the report, there have been 161 Muslim-American terrorist suspects and perpetrators and over 20 terrorist plots by non-Muslim Americans. (A spike of arrests in 2009 is described as an aberration, due to a group of 17 Somali-Americans who joined a terrorist group in Somalia.) Overall, the number of suspects dropped by half from 47 in 2009 to 20 in 2010. The number of individuals plotting against domestic targets also dropped, from 18 in 2009 to 10 in 2010. The analysis provides tables and graphs revealing percentages and numbers of terror suspects and perpetrators since 9/11 to 2010.

Muslims in America Not Radicalizing

Brian Michael Jenkins, “Would-Be Warriors: Incidents of Jihadist Terrorist Radicalization in the United States Since September 11, 2001,” RAND Corporation, 2010

This study provides an overview and brief analysis of homegrown jihadism, arguing that there is no evidence that America’s Muslims are becoming more radicalized. It reports that between 9/11 and the end of 2009, there were 46 publicly reported cases (involving 125 identified people) of domestic jihadist radicalization and recruitment in the U.S. In each case, an average of three people were accused, and half the cases involved only a single individual. The report says “mistrust of American Muslims by other Americans seems misplaced,” given that the number of domestic jihadist recruits is “tiny” out of the total numbers of American Muslims. Jenkins’ study also notes that the 1970s saw far more terrorist violence than what the country has seen in recent years, with 60-70 incidents (mostly bombings) on U.S. soil every year during the earlier period. The report includes a chronology of cases since 2002.

Officials Stir Fear of U.S. Muslims

David Schanzer, Charles Kurzman, Ebrahim Moosa, “Anti-Terror Lessons of Muslim-Americans,” Sanford School of Public Policy, Duke University, 2010

The primary findings of this study are that since 9/11, 139 Muslim Americans (including African-American, Latino and white Muslims) have committed violent terrorist acts, been convicted of terrorism charges involving violence, or been arrested with charges pending. Of those, fewer than a third were successful in executing violent plots and most of those incidents were overseas. The report also points to the media and statements by public officials as a source of unnecessarily ratcheting up fear of Muslim-American terrorism. About half the report focuses on the Muslim-American community’s serious work in denouncing violence, policing potential cases of radicalization, and reporting to law enforcement officials, concluding that this is rarely reported in the media. The study includes an appendix of Muslim-American terrorists between 2002 and 2009 and concludes that the level of Muslim-American terrorism “is small compared to other violent crime in America, but not insignificant. Homegrown terrorism is a serious, but limited problem.”

Recent Upsurge of U.S. Radical Right

Department of Homeland Security, “Rightwing Extremism: Current Economic and Political Climate Fueling Resurgence in Radicalization and Recruitment,” Office of Intelligence and Analysis, 2009

This study noted an upsurge in domestic right-wing extremism and suggested that it was being driven by factors including the election of the nation’s first black president and the worsening economy. It also compared the rise to the upsurge in the radical right that also occurred during the 1990s. The report concluded, among other things, that “lone wolves and small terrorist cells embracing violent rightwing extremist ideology are the most dangerous domestic terrorism threat in the United States.” At one point, the study mentioned the interest among hard-right extremists in recruiting returning war veterans — one of the factors that caused several right-wing politicians and groups to complain that it unfairly targeted veterans and others as potential terrorists. Although this is not what the report in fact said, DHS Secretary Janet Napolitano essentially withdrew the study because of the criticism.

Radical Right Has Grown Since 1990s

Federal Bureau of Investigation, “Terrorism 2002-2005,” undated

This study includes a foreword that details trends in terrorism since the early 20th century. The FBI differentiates between terrorism incidents (acts that actually occurred) and terrorism prevention (acts that were prevented). The report does not include incidents that the FBI classifies under criminal rather than terrorism investigations, which seems to limit its usefulness and skew the statistics it uses to make its points. From 2002 to 2005, for instance, animal rights and environmental rights extremist groups were responsible for 23 of 24 incidents that are listed by the FBI. At the same time, however, the report says that extreme-right individuals and groups were responsible for eight of the 14 recorded terrorist plots (preventions, as opposed to actual attacks). The report also says that in the mid-1990s, right-wing extremism began to overtake left-wing extremism as “the most dangerous, if not the most prolific, domestic terrorist threat to the country,” after the threat from leftist groups receded by the late 1980s. The study provides detailed lists of incidents and preventions by year. According to FBI statistics, there were 318 terrorist incidents in the U.S. from 1980-2005, resulting in 14,038 people wounded and 3,178 deaths.