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?

This paper, written by Silvia D'Amato & Andrea Terlizzi, investigates the extent to which the European Union is strategically engaging against terrorism.

Terrorism destabilizes governments, undermines civil society, threatens social and economic development, endangers democracy, and directly impacts human rights. The extraordinary events on 9/11 turned counterterrorism into a global governance project. The global collaboration is unprecedented with traditional…

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

Terrorist groups adapt to environmental changes to maintain power. This project provides new insights by developing a theory of strategic target selection and using big data analytics and machine learning to test these hypotheses.

This project compares and explains dynamics of cross-border cooperation among European actors in the field of counterterrorism (CT).

Following the terrorist attacks in Paris (November 2015) and Brussels (March 2016), Belgium’s counterterrorism policy has been heavily criticized – domestically and worldwide.

Has there been continuity or change in US counterterrorism policy since 9/11? What factors led to the continuity or change, and how do we classify any such continuity or change?

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

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

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…

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?

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.

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

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…

On 21 March 2019, James Welch defended his thesis 'The Grotius Sanction: Deus Ex Machina. The legal, ethical, and strategic use of drones in transnational armed conflict and counterterrorism'. The doctoral research was supervised by Prof. dr. P.B Cliteur.

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.

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.

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

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…

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

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

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

Professor Edwin Bakker, director of the Centre for Terrorism & Counterterrorism, released his new book “Terrorism and Counterterrorism Studies: Comparing Theory and Practice”, published by Leiden University Press.

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

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?

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?

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.

How do European Muslim men and women become involved in a violent jihadist struggle abroad?

Scholars have long debated the intentions of the Muslim Brotherhood in the Middle East. Some claim the organization supports terrorism, while others believe it is a positive force for democratization.

The Netherlands Ministry of Defense and Ministry of Security and Justice have requested the Centre for Terrorism and Counterterrorism to complete a research project on cyber governance from a policy perspective. The results of this project will contribute to the deliverables of the fourth International…

Intelligence of the crowd, or in other words, intelligence of a large, random collective, exists mostly in social media platforms such as twitter. The collective does not comprise (at least not necessarily) experts on crises, just regular people mostly. Nevertheless, there is valuable intelligence to…

An international comparative study of the Netherlands, Belgium, Denmark, France, Germany, the United Kingdom and the United States.

How do the pathways of Dutch converts to Islam involved in jihadist movements differ from those of Dutch converts who are not, in terms of their life prior to Islam, their conversion experience and the form of involvement with the Islamic community after conversion?

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.

In 2012, the Dutch National Coordinator for Security and Counterterrorism and the Dutch Probation Service launched a reintegration project for offenders on probation or parole who were (suspected to be) involved in jihadist extremism or terrorism. The initiative's primary goal was to reduce the chance…

The MOOC Terrorism and Counterterrorism: Comparing Theory & Practice was one of the first MOOCs of Leiden University to go live back in September 2013. More than three years have passed and the MOOC has attracted over 100,000 people coming from more than 100 countries.

Terrorism experts Daan Weggemans (Leiden University) and Beatrice de Graaf (Utrecht University) conducted one of the first scientific studies on the societal reintegration of jihadist former detainees. They showed that the reintegration process isn't without problems. Their conlusions are presented…

On 12 September 2024, the official ceremony opening the academic year 24-25 for students of the European Law master’s programme took place at Leiden Law School, organised by the Europa Institute.

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…

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.

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

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…