This book presents an understanding of the concept of Countering Violent Extremism from a critical terrorism studies perspective using case studies from different countries while examining the issues it raises.

This research paper seeks to examine the nature of the nexus between right-wing extremism and the military by surveying five potential consequences (i.e., problem areas) arising from the presence of right-wing extremists within the armed forces of twelve Western countries.

Investigating neurobiological endophenotypes of Social Anxiety Disorder

Research goal: To support the design of technologies (counter-measures and communication measures) for the prevention, interdiction and mitigation of lone actor extremist events (LOEEs), which are hard to anticipate, yet can be highly damaging to local and national communities and therefore must be…

This thesis presents pioneering work on the panchromatic emission of some of the most luminous galaxies in the early Universe: star forming galaxies and active galactic nuclei.

With the recent rise and fall of IS, academics and policy makers around the world are expressing concerns about the fate of children of former foreign fighters. Will they follow in their parents’ footsteps? In this paper, Layla van Wieringen, Daan Weggemans and Marieke Liem argue that in light of this…

This paper critically compares seven widely used risk assessment tools for violent extremism, including the VERA-2R, the ERG 22+, the SQAT, the IR46, the RRAP, the Radar, and the VAF.

On 17 August 1945, two days after the Japanese surrender that also brought an end to the Second World War in Asia, Indonesia declared its independence. The declaration was not recognized by the Netherlands, which resorted to force in its attempt to take control of the inevitable process of decolonization.…

A growing amount of literature is being devoted to interrogating gendered dynamics in both violent extremism and terrorism, contributing to the integration of international and feminist security. This includes how such dynamics can shape differences in the motivations and participation of women and…

Training a robot in a real-life environment is more or less impossible. Computer scientist and psychologist Roy de Kleijn switched to training in a simulated, virtual one instead. ‘You do have a reality gap, but the more precisely you train the robot, the better it is in practice.’ His inspiration:…

Global climate change is manifest by local-scale changes in precipitation and temperature patterns, including the frequency of extreme weather events (EWEs). EWEs are associated with a myriad range of adverse environmental and societal consequences, including negative impacts to agriculture and food…

In this thesis new methodologies are developed for the detection and systematic study of radio sources in the early universe. This allows us to gain a deeper understanding of the formation and evolution of galaxies, the activity of supermassive black holes, and the final phase transition of our universe:…

This article examines how the threat of terrorism has been addressed at the policy level through an analysis of a specific case in Mali.

On 12 mei 2020, Darryl Robinson defended 'Exploring Justice in Extreme Cases: Criminal Law Theory and International Criminal Law'. The doctoral research was supervised by Prof. C. Stahn.

In this article, Maria-Elena Kisyova, Yannick Veilleux-Lepage and Vanessa Newby shed some light on how a small but highly visible group of influencers are actively working to promote a dangerous far-right ideology.

In this article, Isabelle Frens, Jelle van Buuren and Edwin Bakker aim to understand anti-government protests by focusing on empty signifiers.

This project explores innovative strategies to counter online extremist content, focusing on integrating traditional content moderation tactics with targeted online interventions. Through research, workshops, and data-driven experiments, we aim to answer: How and when should traditional content moderation…

Doctors and pharmacists should take greater account of obesity when dosing medicines. The distribution in the body and the breakdown of a medicine can vary considerably in obese patients. This is stated by clinical pharmacologist Catherijne Knibbe in the Annual Review of Pharmacology and Toxicology.

The design for the METIS instrument for the Extremely Large Telescope (ELT) is final. The European Southern Observatory (ESO) has given the green light for production of all parts of the instrument. It is the first ELT instrument, designed and to be built under Dutch leadership, to formally pass the…

In this article, Bart Schuurman and Sarah Louise Carthy conduct further research into the understanding of the causes of terrorism by assessing differences and similarities between left-, right- and jihadist extremists and terrorists. The article draws on the Analysen zum Terrorismus, one of the most…

In this publication, the authors explore the reality of accessing and interviewing hard-to-reach populations such as extremists and terrorists

Intergenerational transmission refers to the complex and dynamic process with which values, ideas and behaviors are transmitted across generations. We are specifically interested in the intergenerational transmission of behaviors and beliefs that might result in harm to the individuals involved or society…

This report concerns itself with terrorist technical innovation, particularly with regards to terrorists’ incorporation of emerging technologies into their practices. More specifically, it investigates, through the elaboration of a theoretical learning framework, how terrorist groups can adopt the practices…

On Monday 11 September, Matthew Hoye presented an early draft of a grant proposal on 'Remittance, Paradigms, and Extreme Cases' during a GTGC lunch seminars.

In this paper for Defence Strategic Communications, Alastair Reed and Jennifer Dowling seek to show the importance of historical narratives to propaganda by identifying and exploring five ways in which such narratives are exploited to reinforce the extremists' 'competitive system of meaning'.

Is online radicalisation is an analytically useful concept when discussing contemporary cases of terrorism?

In this article, Bart Schuurman and Sarah Louise Carthy explore the distinctions between radicalised individuals and the general population

The illegal use of hand grenades has generated a lot of public interest over the last few years but very little is known about the nature and extent of these incidents. This research project is trying to fill that gap.

Every summer, Leiden University is the setting of dozens of summer schools in which professionals and students can receive extra training on a specific topic within a short space of time. We took a look at a summer programme on extremism. ‘A recruiter for al-Qaeda said that I could change the world.…

By looking at what is different, researchers often discover the special, the unusual. And that has already brought a wealth of highlights – also in Leiden.

The widely used pesticide thiacloprid can cause a large-scale decline in freshwater insects. This was discovered by researchers from the Living Lab in Leiden. For three months they counted the flying insects in the 36 ditches of the lab. Their research appeared in PNAS.

What influence did the internal debates on the use of violence within left-wing activist movements, and the government’s response to this (political) violence, have on the development, level, and continuity of the violence originating from these movements in the period 1965–2015?

Can behaviour in an online economic game be understood as a representation of radicalisation propensity?

This study is a critical discourse analysis of the misogynistic narratives shared by three incel violent extremists.

Physical chemist Rik Mom developed a revolutionary way to investigate catalysts in action in detail. For this work he received the distinction cum laude during his PhD defence on 29 June.

A professor from Leiden University has subjected various colleagues to intimidating and unacceptable behaviour for a longer period. These are the findings of an investigation carried out by the University’s independent Complaints Committee for Unacceptable Behaviour at the request of the Executive Board…

This research examines how right-wing extremist parents perceive and discuss their role in the ideological socialisation of their children.

When does radicalization not lead to terrorist attacks?

Joseph Callingham from the Leiden Observatory receives the Louise Webster Prize for outstanding post-doctoral research. The prize is awarded by the Astronomical Society of Australia for Callingham’s search for the most extreme object in the Universe.

It is in the interest of all democracies for young people to learn the value of free debate, even on sensitive and potentially divisive issues like terrorism, argue Thorbjørn Jagland (secretary general of the Council of Europe), Sayeeda Warsi (UK parliamentarian), and Francesco Ragazzi (Institute of…

Interdisciplinarity is more than a buzzword in academia. It’s essential for tackling today’s biggest challenges. But what does it look like in practice? How can PhDs learn the skills needed to work across disciplines, and how can supervisors master the art of guiding them?

Since 2012, thousands of individuals have traveled from Western countries to join jihadist groups in Syria and Iraq. While much has been written about these individuals, only sparse attention has been paid to the social environment of these jihadist travelers and, more specific, the role of family members…

Vasiliki Kosta gave a presentation during the session ‘Building Academic Freedom’ taking place at Leiden University on 25 November 2025.

How to minimalize the chance of recidivism for extremist prisoners.