Targeting lone-actor terrorism

An EU-funded project has addressed the threat of violence posed by lone extremists, compiling an extensive database on cases of terrorism linked to such individuals to help prevent future attacks and protect people around the world.

Theme: Security 
Framework programme: Seventh Framework Programme 
Countries involved in the project: Denmark, Israel, Netherlands, Poland, United Kingdom


As with group-based terrorism, lone-actor terrorism spans the ideological spectrum, from right-wing fanaticism to Al-Qaeda-influenced militancy. While the majority of such attacks are not as devastating as those carried out by Norwegian Anders Behring Breivik in July 2011 – which killed 77 people and injured many more – their actions can result in significant loss of life.

Responding to this evolution of terrorism, researchers from the EU-funded PRIME project assembled what they believe to be the world’s largest collection of data on terrorist cases linked to lone individuals.

The knowledge can be used to improve risk assessment and intelligence gathering, and reduce opportunities for terrorist acts carried out by individuals acting alone. Results have been shared with international law enforcement agencies.

‘We didn't stop at data collection and analysis but worked to develop the foundation for robust analytical tools grounded in criminological research,’ says PRIME project coordinator Noémie Bouhana of University College London in the UK. ‘We wanted to go beyond traditional statistical analyses by introducing new methods to analyse the sequence and relationships between risk indicators, to advance the state-of-the-art in risk analysis.’

Growing concern
Because they have the potential to inflict considerable human, social and political harm, terrorist attacks carried out by lone individuals are highly damaging and have been a growing source of concern to security services.

However, the PRIME researchers – an international consortium of experts – acknowledge that such attacks are relatively rare compared to other types of crime.

‘Yet that very rarity means that opportunities to learn from experience are limited, and that is what makes these acts of violence hard to detect, disrupt and recover from,’ says Bouhana.

The PRIME database includes sociodemographic and non-sensitive information on the majority of individuals who engaged in, or planned to engage in, lone-actor terrorist attacks within the United States and Western Europe and were convicted for their actions or died while committing them between 1990 and 2015.

Researchers also accessed unique data, some of it confidential but entirely anonymized, on lone-actor terrorist events in Israel and the West Bank between 2000 and 2016.

All the work was carried out with ethical oversight and with respect to the fundamental rights of the individuals concerned.

Social behaviour
First and foremost, PRIME findings challenge the pertinence of the ‘lone wolf’ moniker often used to describe terrorists who strike solo and have no apparent links to any groups.

‘Lone terrorists do not emerge out of a vacuum, which is good news for our capacity to acquire intelligence and detect these individuals ahead of their violent actions,’ says Bouhana.

Ties to online and offline radical communities are critical to the adoption and maintenance of both the motivation and the capability of a person acting alone to commit terrorism. In general, their radicalisation is a social process, requiring interaction with others, even if, paradoxically, this process results in social isolation.

In terms of pre-attack behaviour, analyses show that the majority of lone actors are not the stealthy and highly capable terrorists that the term ‘lone wolf’ might imply. Many of them are poor at maintaining operational security and often, sometimes months or even years in advance, leak their beliefs or intentions to the people around them.

Such terrorists also share common patterns with more ‘run-of-the-mill’ criminals in that they are more likely to select a target in an area close to where they live.

Analyses of vehicle-enabled attacks by single individuals in Israel and the West Bank show that, in the same way that crime concentrates in hotspots, these types of attacks occurred on ‘hot routes’. This suggests that approaches popular in crime prevention, which advocate making changes to the environment to make crime more difficult, also show promise against this type of threat.

No profile of a lone terrorist emerged, but in a significant number of cases an inclination for criminality and violence was evident before the individual concerned became radicalised.

A key PRIME finding with important implications for risk analysis is that the same indicators – such as those related to the terrorists' mental health – can matter in different ways for different individuals at different points in their trajectory. This motivated the development of a risk analysis framework intended to act as a ‘diagnostic guide’.

In terms of public communication campaigns, PRIME found that more should be done to clarify and define suspicious behavior.

‘Uncertainty as to what is ‘suspicious’ is a barrier to reporting it,’ says Bouhana.

The project team's analysis of press coverage suggests that the media can have both positive and negative effects. While reports of the counter-terrorism strength of a particular country may potentially deter attackers, details of counter-terrorism weaknesses and state vulnerabilities could aid potential lone terrorists in planning attacks, the project concludes.

Project details

Project acronym: PRIME
Participants: United Kingdom (Coordinator), Poland, Denmark, Israel, Netherlands
Project N°: 608354
Total costs: € 3 590 953
EU contribution: € 2 842 878
Duration: May 2014 to April 2017

See also:

  • Project website
  • Project details