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.

The Una Europa Clusters bring together leading experts and experienced staff from numerous academic and professional service departments across the Una Europa institutions.

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.

Many galaxy clusters exhibit bright diffuse radio emission that traces the underlying structure of the intracluster medium (ICM).

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.

Promotor: Prof.dr. H.J.A. Rottgering, Co-promotor: David Sobral

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

In this book, Sarah Giest, Assistant Professor at the Institute of Public Administration, provides insight into the collaborative and absorptive capacities needed to provide public support to local innovation through cluster organizations.

In the era of big data, extracting insights from complex datasets is a key challenge. This thesis demonstrates the superiority of graph-based methods over traditional clustering (e.g., k-means, DBSCAN) and outlier detection for analyzing high-dimensional and noisy data.

This thesis focuses on the X-ray spectral analysis of merging galaxy clusters and the plasma code development for future high-resolution X-ray spectroscopy observations.

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

Promotor: Jelle S. Kaastra Co-promotor: Jelle de Plaa

The largest structures in the Universe are clusters of galaxies. Each can contain hundreds to thousands of galaxies.

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

Security and Legitimacy is one of the three organisational clusters of the Institute of Political Science.

Promotor: Koen Kuijken Co-promotor: Henk Hoekstra

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.

CADS researchers give methodology their own unique signature through two parallel engagements: (a) teaching and researching the full range of social science methods, from audio-visual engagements, through global ethnography, to statistical analysis; and (b) interrogating these multiple modalities employing…

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.

My PhD research is devoted to studies of the conjectural cluster-algebraic symmetry in the theory of topological string, which is the simplest, however already non-trivial sector in the theory of string.

The CADS Research Cluster People, Power and Diversity aims to further theoretical and methodological debates on the classifications of human difference, such as gender, race, ethnicity, sexuality, class, age, ability, religion, level of development, time, etc., and the way these classifications organize…

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.

The CADS Asia Research Cluster extends the legacy of the Institute’s Asia focus into the future, as an important hub in international networks on the study of Asia and through active engagement with colleagues in Asia. Within the Institute the Asia Research Cluster offers a platform for anthropologists…

International Relations and European Politics is one of the three organisational clusters of the Institute of Political Science.

The origin and evolution of galaxies are closely linked to many different physical phenomena.

The d12n Research Cluster provides a space for inquiry and intervention into the ongoing digit(al)isation of culture, society, and scholarship. The research cluster aims to link CADS Institute researchers to each other as well as to experts and praticioners from around the world as we combine thinking…

On the largest scale, the Universe resembles a cosmic spiderweb. Most galaxies coexist in small groups within the threads of this web. At the nodes of the threads are enormous groups of galaxies forming the largest structures in the universe still held together by gravity: clusters of galaxies.

In this thesis, I study the formation of large-scale structure and the physics of particle acceleration at large scales (~Mpc).

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…

The Sustainability Research Cluster fosters dialogue and collaboration among anthropologists and sociologists researching aspects of socio-cultural, ecological, and economic sustainability in and affiliated with the Institute of Cultural Anthropology and Development Sociology. It also seeks to stimulate…

Promotor: P. T. de Zeeuw, Co-promotor: N. Neumayer; G. van de Ven

Promotor: Prof.dr. K.H. Kuijken, Co-Promotor: Dr. H.Hoekstra

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 monograph focuses on clustering of objects in high-dimensional data, given the restriction that the objects do not cluster on all the attributes, not even on a single subset of attributes, but often on different subsets of attributes in the data.

In this thesis, I studied the origin and evolution of the non-thermal radiation in merging galaxy clusters.

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…

Forming at the nodes of the Cosmic Web and growing hierarchically via mass accretion, galaxy clusters are the largest virialized halos in our universe, composed of dark matter (DM; ≥85%), ionized hot plasma in the intracluster medium (ICM; ≥10-15%), and galaxies (≥1-5%).