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

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…

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.

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…

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.

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…

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 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.

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.

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…

This report examines the questions

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…

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.

The question of how military interventions can best transition to a long term counter-terrorism policy forms the core research question of three interlinked reports. This research project has been completed with support of NATO’s Science for Peace and Security Programme. Leiden University researchers…

An interview with Assistant Secretary General for Emerging Security Challenges David van Weel, and NATO Secretary General’s Special Representative for Women, Peace and Security (WPS) Clare Hutchinson

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.

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

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…

This article presents an in-depth evaluation of a specialized reintegration initiative within the Dutch Probation Service focused on individuals convicted or suspected of involvement in terrorism.

This paper contributes on an increasing body of work on radicalisation. It specifically focuses on what distinguishes individuals whose behavioural radicalisation includes involvement in terrorist violence from those whose behavioural radicalisation does not.

This article presents the findings of an explanatory study into the perceptions of Dutch Muslims in The Hague concerning pre-emptive counter-extremism and de-radicalisation policies.

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

In this article, Tokdemir & Klein examine the strategic actions of governments against domestic terrorist groups and domestic terrorist groups’ reactions to such actions.

The book addresses the question “How and why do people become involved in European homegrown jihadism?

This research sets out to answer the following questions:

The study by Tahir Abbas and Liselotte Welten reveals a structural and nuanced understanding of how the question of Salafism in the Netherlands has become an increasingly discussed phenomenon and the types of threats that ought to give genuine concern to security, intelligence and policing services.

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…

On 8 March 2023 Helen Duffy, Professor of International Human Rights and Humanitarian Law in Leiden, published a monograph on Global Trends in Counter-terrorism and the Implications for Human Rights in Africa.

The second and final report on the Netherlands‘ crime-terror nexus has analysed all fourteen profiles of individuals arrested in 2015 for offences of terrorism.

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.

What is the current relevance of the ethics of counterterrorism and what is the added value of ethics support within the practice of counterterrorism?

Ragazzi, ‘Suspect community or suspect category?‘, Journal of Ethnic and Migration Studies

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.

This article provides a comprehensive analysis of the Islamic State's use of images taken by drones, drawing on a dataset of ISIS propaganda images from October 2016 to December 2018.

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?

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).

This study presents the findings of a laboratory-based experiment testing hypothesised processes implicated in the prevention of violent radicalisation through counter-narratives. The central aims of the study were to contribute to counter-narrative theory, whilst highlighting the value of experimental…

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

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 article explores how ISIS and the Taliban have fostered support through their parallel legal systems.

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.

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.

Could policies aimed at preventing radicalisation undermine the very trust and social cohesion they aim to strengthen?

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