Homegrown terrorism

Jytte Klausen examines what sort of people are driven to acts of extremism and why

The concept of ‘homegrown’ terrorism was born in the aftermath of the 2005 London Underground attacks and gained prominence as more terrorist incidents committed by European and North American militants in the name of the movement Bin Laden started in the Nineties unfolded. The concept has no legal meaning and cannot easily be translated into clean sociological distinctions but raises a real and important question.
It is often assumed in discussions of homegrown terrorism that young Muslims are driven to violence by anger over discrimination and alienation stemming from their treatment in the West. If that were true, they would surely vent their anger on symbols close at hand, in their home country. In fact, however, the Western militants above all want to travel abroad and become mujahideen. They are driven not by anger against their circumstances at home, but rather by an adventure-seeking urge to find a new religious utopia and to join the fight abroad. Anger and revulsion may be cited as justifications for violent acts, but usually those statements follow ideological scripts after they have joined rather than giving authentic accounts of their passage to militancy.
This is the conclusion that emerges from analysis of data from The Western Jihadism Project, a data collection that I initiated in 2006, that tracked 7,000 Western residents who committed terrorism offenses on behalf of al-Qaeda and associated groups – including the splinter group known as the Islamic State. Over half of the individuals in the dataset who qualified as native-born became foreign fighters or attempted to join a terrorist organisation abroad. All the data derives from public sources and was manually encoded into a digital portal utilising relational – SQL – data management, which makes it possible to coordinate datapoints across different variables.
The database deploys a range of demographic and social variables. One distinguishes immigrants and those we call native-born, the cohort targeted by the homegrown concept. We identified and coded 724 US residents and citizens who, between 1990 and 2019, committed domestic terrorism-related offenses or travelled abroad to join a jihadist insurgency, or who are known to have died abroad in connection with terrorism-related actions or to still be abroad embedded with a terrorist organisation. To be included as native-born a person has to be either an American citizen or have arrived in the United States before the age of 14, lived in the United States during their formative teenage years and radicalised in the United States. People who moved there as adults and became citizens by naturalisation are coded as ‘immigrant’.
By these criteria, 485 (67 percent) individuals were ‘homegrown’ American jihadists. American extremists are less – much less –likely to have the thick network connections to others who joined the global movement and to foreign terrorist groups. When they carried out terrorist attacks, they sometimes received instructions from movement operatives based abroad, either by travelling and obtaining training in bomb making and terrorist trade craft or from online contacts. More often they acted on their own, with inspiration and assistance from friends and coaches they found online. Therefore, the Americans are rather better exemplars of ‘homegrown’ terrorism than the networked Europeans. 227 (36 percent) were converts, meaning that they did not grow up with Muslim parents, but at some point converted to Islam. This may come as a surprise, but other studies arrived at similar estimates from datasets that were put together using slightly different inclusion criteria.)The timing of their conversion can be tricky to assess, but we found that many – certainly a majority – converted to Islam at more or less the same time as they embraced extremism. To put it another way, they found Islam through the extremist programme rather than finding extremism through Islam.
The median age at which the Americans in our database of jihadist offenders first committed a terrorism-related crime was 26. This too may come as a surprise. The stereotype is that jihadism is a young person’s crime, like gang membership. In fact, jihadist terrorism is generally an adult crime. However, age was relevant to what sort of crime was involved.
Violence is generally committed by younger people. Nonviolent offenders were on average 10 years older than those who became foreign fighters: 32.5 versus 23 (median values). Those who undertook a violent terrorist act at home were on average four years older than the ‘foreign fighters’, the Americans who travelled abroad to join a foreign terrorist group. Younger people go abroad to join an insurgency. Older people stay at home, either to carry out a domestic attack or to undertake support roles. Still, the standard deviation was large: 6.5 years in the case of the foreign fighters. The youngest foreign fighter was 15 and the oldest 40.
To sort out who chose to do what, we identified four trajectories or roles. These were treated as dependent variables in a regression analysis. Demographic variables (convert, native-origin natural-born Muslim and immigrant-origin Muslim) were the independent variables. The first category included nonviolent supporters who went in for fundraising, recruiting and proselytising efforts related to terrorism that were not protected under US First Amendment rights to advocate for extremist politics. A second set chose to commit violent attacks in the USA. A third set tried to go abroad to fight for a foreign terrorist organisation. The fourth was made up of those who carried out a domestic act of terrorism and also sought to join a foreign organisation.
Binary logistic regression tests were used to estimate the odds that a person with particular demographic characteristics would be expected to undertake each of the four types of engagement. The output metric is an odds ratio, which represents the constant effect of the independent variable on the outcome. This yields an estimate of what proportion of a demographic group in the study engaged in a particular type of action as compared to people who did not belong to that group. For example, converts may be compared with non-converts with respect to the likelihood that they will join a foreign insurgency.
When interpreting the results, it is important that violent extremism is a marginal, low-base number phenomenon. A rough estimate is that fewer than 0.02 percent of American Muslims participated in terrorist activities between 2001 and 2019. (The estimate assumes that three and a half million Muslims live in the United States.) If a particular class or a category of activities or pathologies is rarely observed in the general population, it is difficult to study – or treat – the phenomenon using traditional statistical methods. Vice versa, it is also not possible to make inferences from this marginal group about the behaviours of the general population. The results only throw light on which roles different groups of extremists choose as they join the movement and what that may say about their motivations.
It turned out that converts were nearly three times as likely (2.7:1) to become foreign fighters as non-converts. Men are six times (6.0:1) more likely to commit violent offenses – both domestic and abroad – than women. This is not a surprise as the movement generally has not approved of women becoming warriors. Some of the other effects of demography on role types were more limited, although still solid. Native-born individuals in the database were nearly twice as likely (1:7:1) to become foreign fighters as were the immigrants. Muslims born or brought up in the USA are less likely to participate in domestic attacks (0.37:1). Immigrant-origin extremists are disinclined to become foreign fighters (0.6:1).
The older people get, the less likely they are to commit violent offenses (although the effect was relatively weak). Age had a significant but moderate effect on the likelihood of becoming a foreign fighter. The odds ratio is 0.9:1, suggesting that as the militants age, they are less likely to become foreign fighters. It is plausible that older people might be averse to violent roles, but the relationship between age and the propensity for violent acts is rather fuzzy. There was no significant relationship between age and becoming a violent domestic operative. Older militants may carry out domestic attacks, but are far less likely to become foreign fighters.
Close to 8 percent (57) of the extremists we coded were women. Women are generally engaged in nonviolent support activities (raising money, buying tickets for people, posting threats online) and going abroad to join the struggle, although a few women attempted to carry out domestic attacks. Judging from their acts and their own statements, women appeared to mostly be fired up by the idea of becoming a wife of a warrior or a soldier for the jihadist revolution in a far-flung location with which they had no natural-born connection.
What then are their basic motivations? Motivations are complex and cannot easily be generalised. No one-size-fits-all theory can explain why somebody becomes a terrorist. And people’s motivations change. The personal experiences or personality traits that initially lead a person to adopt extremist beliefs or to join a radical group may at a later time give way to quite different ideological motives when the person is ready to carry out a violent strike or to become a suicide bomber. They may be ‘homegrown’ in the sense that the Western militants form their beliefs while living in the West, but judging by their actions young native-born Muslims and converts to Islam are excited by the vision and opportunities promised by the recruiters to become part of a movement or simply want to travel to jihadi hotspots in order to be a ‘big man with a gun’. Those who choose to stay home to ‘do something’ often do so after their dream of going abroad is thwarted by lack of a passport or connections to bridge their journey. And then there are those who – similarly to the London Underground bombers – go abroad and then return home to carry out their terrorist attack.

Jytte Klausen is the Lawrence A Wien Professor of International Cooperation at Brandeis University and an Affiliate at the Center for European Studies at Harvard University. She founded the Western Jihadism Project in 2006 with the aim of providing an integrated approach to demographic research and network analysis of Western violent extremists associated with al-Qaeda and the study of extremist Islamist ideology. She is the author of Western Jihadism—A Thirty-Year History published by Oxford University Press in August 2021.