This project aims to improve understanding of, and responses to, the phenomenon of lone actors through analysis of comprehensive data on cases from across Europe.

This article provides an in‐depth assessment of lone actor terrorists’ attack planning and preparation.

The term “Lone Actor” has been applied to a variety of violent individuals who are thought to act out of ideological motivations using terrorist tactics.

Why does one person radicalize to involvement in terrorist violence within a group-based context, while another engages in this form of violence alone?

Understanding the evolving landscape of extremism in the 21st century.

This research note argues that the “lone wolf” typology should be fundamentally reconsidered.

Jeanine de Roy van Zuijdewijn, researcher and lecturer at ISGA, was a guest on NPO Radio 1 where she discussed the attacks carried out in 2011 by Anders Breivik.

Terrorism has been one of the most important threats to peace, security and stability in many parts of the world. But what does this mean? What is the nature of this threat? What can be done about it and how can we at least limit the impact of terrorism?

When does radicalization not lead to terrorist attacks?

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…

Recently, Europe was again shaken by some attacks. This ‘Elementair Deeltje’ places terrorism in a historical perspective and gives an up-to-date overview of this form of political violence.

Refugees’ effect on domestic terrorism is conditioned by host-country social perception (attitude about living next-door to foreigners) and economic competition. These hypotheses are tested cross-nationally from 1995-2014 leveraging data from the World Values Survey.

During the 1980s and early 2000s, authors like Alex Schmid and Andrew Silke demonstrated the paucity of first-hand insights being used to study terrorism and the consequences this had for the reliability of the findings beings presented. But to what extent have these issues endured?

This reflection for Critical Studies on Terrorism, explores two decades of the 'War of Terror' and what it means today.

Jelle van Buuren bespreekt de link tussen radicalisering en psychiatrische problematiek.

On 20-21 June, the Society for Terrorism Research (STR) held its annual conference in Oslo. The Center for Research on Extremism (C-REX) of the University of Oslo led by Professor dr. Tore Bjørgo hosted one of the main academic conferences in the field of terrorism studies. The central theme was the…

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…

As terrorism scholars, we are intrigued by those who engage in violence. We study their motivations, tactics, ideology, organisational structures, and pathways to (de-)mobilisation, hoping to better understand terrorism and how we can counter it. Far less attention is paid to what happens after an attack…

Terrorism only poses a small risk to people but tends to be a major source of public fear. Through fear, terrorism has far-reaching implications for public governance.

In the track Governance of radicalism, extremism and terrorism you will be familiarised with the academic debate regarding these contested concepts.

This article researches the public perception of terrorist attacks by measuring the importance the public assigns to attributes of terrorist attacks.

This book contextualizes the use of terror as part of wider movements of political contention, demonstrating that terroristic innovation occurs as part of wider historical processes rather than in a vacuum.

Can conspiracy constructions explain for hatred of the system? And if so, should conspiracy constructions be considered to be a risk in terms of national security?

In December 2014, Leiden University’s Institute of Security and Global Affairs with the Australian National University’s Asia-Pacific College of Diplomacy and the International Centre for Counter-Terrorism, commenced a research project to assess how (temporary) military interventions can best prepare…

In this article, Yannick Veilleux-Lepage and Tommy van Steen, assistant professors at the Institute of Security and Global Affairs, discuss the degree of consensus within the field of terrorism studies regarding the impact of the COVID-19 pandemic on the activities of violent non-state actors.

Our courses are aimed at higher educated professionals, starters, experienced professionals and managers. You can choose from day-long Masterclasses, multi-day courses and an intensive one-year program. Our English courses about Terrorism, Law, Safety and Security are listed below.

Promotor: F.S. de Boer Co-promotor: P. T. de Gouw

This six-weeks online course delves into the research behind terrorism as it unpacks the assumptions and impacts of both terrorism and counterterrorism.

A cautious response to a crisis or terrorist act avoids the creation of a culture of fear. This is another way to reduce our vulnerability to terrorism.

Jeanine de Roy van Zuijdewijn, PhD candidate at ISGA, explained the dilemma countries face in the aftermath of terror attacks.

This paper investigates possible convergence of issue salience of terrorism among citizens within the European Union for ten jihadist attacks in the period 2015–2017 using Eurobarometer survey data.

This research paper was requested by the European Parliament's Committee on Civil Liberties, Justice and Home Affairs. It was published by the International Centre for Counter-Terrorism (ICCT) in The Hague. Leiden University is one of the participating institutes in this publication and our researcher…

This article written by Marieke Liem & Alexander Kamprad investigates the relationship between terrorism and interpersonal violence. They conducted cross-national analyses on the effects of terrorism mortality rates on homicide rates. Results showed that terrorism appears to be robustly and positively…

In recent years, the use of primary data in terrorism research has increased. In order to maximise the benefits of this trend, we want to encourage terrorism scholars to implement open science practices more systematically. This article therefore presents different avenues towards open and reproducible…

Terrorist attacks are not an end in themselves, but a means of creating unrest and fear. Terrorism policies and research should focus more on managing fear and social unrest.

Few events have influenced our global order as intensely as the events of September 11, 2001.

Study information

Study information

The authors detail the transnationality of terrorist organisations, including fundraising, communications, alliance-forming, movement and target selection.

This collection includes six short policy-focused contributions exploring how legislation and policy on counter cyber terrorism unfold at the national level in the United States, the United Kingdom, China, Russia, France, and at the regional level of the European Union.

In this article, the authors analyse two major factors that deepen informality, namely multipolar geopolitics and the rise of non-state actors.

In this article for Studies in Conflict & Terrorism, the authors analyse the evolution and interplay of national policies and international diplomacy on cyber terrorism within and across the UNSC’s permanent five members and the UN process on cyber norms (GGE and OEWG).

Self-censorship violates principles of a free society but few people want to take the role of the martyr.

How have British, Dutch, and German security services dealt with political violence and terrorism since the late 1960s; to what extent did they consider these new phenomena as a task and how have they developed activities in order to counter these security threats?

Political scientist Nicolas Blarel (Leiden University) analsyses how non-state actors can (directly or directly) attempt to provoke conditions for a crisis between state actors that have nuclear capabilities. He argues that there is an urgent but complicated and understudied task to understand and manage…

Are you thinking about studying Crisis and Security Management: Governance of radicalism, extremism and terrorism? Learn more and watch the videos.

These three repors are part of a research project that assesses how military interventions can best prepare the ground for an effective long-term counter-terrorism policy. Three different cases have been studied, and they have each provided the input for the policy relevant recommendations that are…

What should policymakers and politicians do to prevent violent extremism? What are the greatest risks posed by the radical left and right? How do ideological media publications that terrorists assemble before attacks, may help to counter extremist narratives? About 30 professionals from all over the…

In this article, Jeanine de Roy van Zuijdewijn and Edwin Bakker provide a big picture reflection on two decades after 9/11 in Western Europe.