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?

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

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…

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…

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.

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.

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

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

In the track Terrorism and Political Violence you will be familiarised with the academic debate regarding these contested concepts.

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…

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

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.

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.

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…

Are you thinking about studying Crisis and Security Management: Terrorism and Political Violence ? Learn more and watch the videos.

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.

When does radicalization not lead to terrorist attacks?

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…

The Terrorism and Political Violence research group at Leiden University examines the causes of radicalisation, the tactics of extremist groups, and the effectiveness of counter-terrorism policies. We also explore the role of the media and the influence of postcolonial legacies in the Global South,…

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…

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

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).

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…

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?

Comparing terrorist attacks with falling off a step ladder is absurd, writes Jeanine de Roy van Zuijdewijn in NRC Handelsblad on 27 September 2017.

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

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

Jasper de Bie, who obtained his doctoral degree at the Institute of Criminal Law & Criminology and who is currently employed by the Ministry of Security and Justice, has been awarded an honourable third place in the international competition 'TRI Award for the Best Doctoral Dissertation on Terrorism…

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.

From the research Terrorist threat in the Netherlands, the risk perception and opportunities for risk communication (Leiden University) shows that the Dutch respond relatively sober to attacks in neighboring countries and the possible risks of a terrorist threat. Half of the respondents believe that…

This report examines the questions

Academic research on terrorism is getting better all the time. This is the conclusion of university lecturer Bart Schuurman after studying 3,442 articles. He published his study in Terrorism and Political Violence.

Jeanine de Roy van Zuijdewijn teaches the masterclass terrorism 2018 together with Edwin Bakker. Read the interview here.

The MOOC Terrorism and Counterterrorism: Comparing Theory & Practice by Prof. Edwin Bakker, co-developed by the Centre for Innovation, has now attracted over 100,000 participants. It is the first MOOC of Leiden University to reach this magic number.

Are terrorist suspects willing to reintegrate back into society? Can they reintegrate?

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

You can find more information on the Dutch webpage. Click on the “Nederlands” button above.

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

Acquiring and maintaining public support is frequently cited as an important requirement for governments fighting non-state actors. But how exactly can public support influence the course of counterterrorism campaigns and thereby contribute to an escalation or de-escalation of violence?