By Jeff Gruenewald, Associate Professor and Director of the Terrorism Research Center, University of Arkansas; Joshua D. Freilich, Professor of Criminal Justice, City University of New York; Steven Chermak, Professor of Criminal Justice, Michigan State University; William Parkin, Assistant Professor of Criminal Justice, Seattle University; and Brent Klein, Assistant Professor, Department of Criminology and Criminal Justice, University of South Carolina

On a Tuesday morning in September 2001, the American experience with terrorism was fundamentally altered. Two thousand, nine hundred and ninety-six people were killed as the direct result of attacks in New York, Washington DC, and Pennsylvania. Thousands more, including many first responders, later lost their lives due to health complications from working at or being near Ground Zero. Nineteen years later, the image of terrorism for most Americans remains tied to that morning.

The 9/11 attacks were perpetrated by al-Qaida terrorists. They resulted in nearly 18 times more deaths than America’s second most devastating terrorist attack – the Oklahoma City bombing that occurred 15 years earlier. That intense loss of life has meant that the 9/11 attacks have come to symbolize terrorism for many Americans.

But focusing solely on Islamist extremism groups like al-Qaida when investigating, researching and developing counterterrorism policies does not necessarily align with what the numbers tell us. Homegrown far-right extremism also poses a persistent and lethal threat to the lives and well-being of Americans. This risk is often underestimated because of the devastating impact of the 9/11 terrorist attacks.

By the numbers

Historically, the United States has been home to adherents of many types of extremist ideologies. Our 15 years of research shows the two current most prominent threats are motivated by Islamist extremism and far-right extremism.

To help assess these threats, the Department of Homeland Security and the Department of Justice have in the past funded our work with the Extremist Crime Database (ECDB), collecting data on crimes committed by ideologically motivated extremists in the U.S. Our analyses of that data are published in peer-viewed journals and on the website for the National Consortium for the Study of Terrorism & Responses to Terrorism. The ECDB includes data on ideologically motivated homicides committed by both Islamist extremists and far-right extremists going back more than 25 years.

Between 1990 and 2019, the ECDB identified 47 events in the U.S. motivated by Islamist extremism that killed 154 people. When you include 9/11 as a singular event, those numbers jump dramatically to 48 homicide events and 3,150 people killed. The database also identified 217 homicide events motivated by far-right extremism, with 345 killed. And when you include the Oklahoma City bombing, it rises to 218 homicide events and 513 killed.

The locations of violent extremist activity also differ by ideology. Our data show that between 1990 and 2019, most Islamist extremist attacks occurred in the American South (51%), and most far-right extremist attacks occurred in the West (36.7%). Both forms of violence were least likely to occur in the Midwest, with no incidents committed by Islamist extremists and 25 events committed by far-right extremists (11.5%).

Our research has also identified violent Islamist extremist plots against 333 targets that were either foiled or failed between 2001 and 2019. Many of the same Islamist extremists are responsible for plotting against multiple targets simultaneously. On average, 18 various sites in the United States are targeted every year, with civilians and military personnel ranking as the most likely to be targeted, and New York City, and Washington DC ranking as the cities most likely to be targeted. The FBI was responsible for thwarting two-thirds of the Islamist extremist plots identified by the ECDB during this time frame.

We are still in the process of compiling similar data on far-right plots. Although data collection is only about 75% percent complete for failed and foiled extreme far-right plots, we have already identified over 800 violent far-right extremist targets between the same time period, making clear that the absolute numbers are much higher.

Motives and methods

There are also differences in demographics, motives and methods for different types of extremists. For instance, guns continue to be the weapon of choice in approximately 74.5% of Islamist extremist homicides and in only 54.6% of far-right extremist homicides. We attribute these differences to far-right extremists using forms of violence that include beating or stabbing victims to death.

We have also found that suicide missions are not unique to Islamist extremists. From 1990 to 2019, we identified ten suicide missions in which at least one person was killed connected to Islamist extremism, including the 9/11 attacks as one event. In contrast, there were 16 suicide missions committed by far-right extremists.

Our analyses found that compared to Islamist extremists, far-right extremists were significantly more likely to be economically deprived, have served in the military and are more involved in the the extremist movement. Far-right extremists were also significantly more likely to be less educated, single, young and to have participated in training by a group associated with their extremist ideology.

Threat to law enforcement and military

Terrorists associated with Islamist extremism and far-right extremist ideologies do not only attack civilians. They also pose a deadly threat to law enforcement and military personnel. During the Sept. 11, 2001, terrorist attacks, 72 law enforcement officers and 55 military personnel were killed by members of Al-Qaida. On April 19, 1995, 13 law enforcement officers and four military personnel were killed when the Alfred P. Murrah Federal Building was bombed by an anti-government far-right extremist in Oklahoma City.

Apart from these two events, Islamist extremists are responsible for the murders of 21 military personnel in four incidents, and eight law enforcement officers were killed in six incidents between 1990 and 2019. Far-right extremists have murdered 59 law enforcement officers in 48 incidents, but have never directly targeted military personnel.

Far-right extremists, who typically harbor anti-government sentiments, have a higher likelihood of escalating routine law enforcement contacts into fatal encounters. These homicides pose unique challenges to local law enforcement officers who are disproportionately targeted by the far right.

Moving forward

The events of 9/11 will continue to skew both our real and perceived risks of violent extremism in the United States. To focus solely on Islamist extremism is to ignore the number of murders perpetrated by the extreme far right and their place in a constantly changing threat environment. At the same time, to focus solely on far-right extremism is to ignore the extraordinary lethality of Islamist extremist attacks.

Some experts have even warned that there is potential for collaboration between these extremist movements. Our own survey research suggests this is a concern of law enforcement. Focusing on national counterterrorism efforts against both Islamist extremism and far-right extremism acknowledges that there are differences between these two violent movements. Focusing solely on one, while ignoring the other, will increase the risk of domestic terrorism and future acts of violence.

Both ideologies continue to pose real threats to all Americans. Evidence shows far-right violent extremism poses a particular threat to law enforcement and racial, ethnic, religious and other minorities. Islamist violent extremism is a specific danger to military members, law enforcement, certain minorities, and society at large. It remains imperative to support policies, programs and research aimed at countering all forms of violent extremism.