Which is the Bigger Threat: Offline or Online Radicalization?
The sample of perpetrators and attacks was drawn from existing databases for terrorist attacks, including the START Global Terrorism Database, the George Washington’s Program on Extremism database of attacks in the West, the French National Assembly’s database of terrorist attacks in France, the UK’s Independent Reviewer’s database of Terrorism, the database of plots in Spain from Observatorio Terrorismo and Seguridad Internacional, and more. In addition to the information contained in these databases, we identified further attacks and plots through open‐source research. This included access to court documents from each of the countries in the database. Moreover, we conducted dozens of interviews with police investigators, family members and friends of attackers, lawyers and others close to the cases.
Our findings suggest that the primary threat comes from those who have mostly been radicalized offline. More than half of the individuals in our database were radicalized mostly offline versus a significantly smaller number who were radicalized mostly online (54% vs 18%). Individuals radicalized mostly offline were significantly more likely to complete their attacks than those who were radicalized online (29% vs 12%). However, we found that the number of people being radicalized online has increased over the last seven years, primarily in the youth demographic. Nonetheless, even in this demographic online radicalization has not surpassed offline radicalization.
Cases of online asocial radicalization (by which we mean exposure to online propaganda with no known social interaction) accounted for only 2% of cases. Foreign terrorist fighters (FTFs) were equally as likely to carry out their attacks as non‐foreign terrorist fighters (29% and 28%, respectively). More than 60% of completed attacks were committed by lone actors (67%). The best completion rate was for individuals who were radicalized offline and acted alone (60% completed an attack). Most individuals fitting this profile were either known to the police and/or under surveillance (68%) and had a criminal record or had been imprisoned (74%). A significant proportion of them were foreign fighters (26%). Nonetheless, 35% had radicalized friends or family even though they attacked alone.
Groups, regardless of radicalization setting, achieved a significantly lower completion rate (15%). Even those who radicalized offline but attacked in groups had a low completion rate (19%), which is three times lower than lone actors who were radicalized offline but completed their attacks.
Yet people who had been radicalized offline acting in groups were 15% more lethal than when they attacked alone. Under half of these group actors were under surveillance or known to counter‐terror (CT) police (44%, 1.5 times less likely to have been under surveillance or known to CT police than offline‐radicalized lone actors who completed their attacks) or had been in prison previously (47%). People who had been radicalized online, both singly and in groups, accounted for only 12% of successful attacks.
Unlike other studies, our database consists of only those who have completed an attack or were thwarted before being able to do so. Therefore, it gives a more accurate picture of the actual threat landscape over seven years in eight Western countries than studies based on surveys or less representative sampling techniques. Our findings show that the primary threat still comes from those who have been radicalized offline. Offline‐radicalized individuals are greater in number, better at evading detection by security officials, more likely to complete a terrorist attack successfully and more deadly when they do so.
