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.

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.

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.

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.

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.

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 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,…

When does radicalization not lead to terrorist attacks?

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

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

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).

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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?

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

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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…

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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.

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

Preventing terrorism before it happens seems like an idea no one would disagree to. But is it possible? How do counter-radicalisation policies look like? And are there dangers of unintended consequences? Francesco Ragazzi, Assistant Professor at Leiden University’s Institute of Political Science, has…

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…

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

De Roy van Zuijdewijn, researcher and lecturer at the Institute of Security and Global Affairs, wrote an opinion piece on the ongoing threat still being posed by Jihadism in Dutch newspaper NRC.

What is the impact of terrorism? Researchers Jeanine de Roy van Zuijdewijn and Jessica Sciarone looked at ten jihadi attacks and concluded that there are major differences between European countries.

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.

The ‘Community Resilience Fund’, a programme of the Canadian federal government, approved a research grant for Dr. Bart Schuurman of the Institute of Security and Global Affairs.

On 15 March, the 28-year-old Australian right-wing extremist Brenton Tarrant committed a terrorist attack on two mosques in Christchurch in New Zealand. Jelle van Buuren, Bart Schuurman, Daan Weggemans and Tahir Abbas all working at the Institute of Security and Global Affairs (ISGA) have been approached…

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…

This report examines the questions