«Western Jihadism is a groundbreaking analysis of a global movement about which we often hear but tend to lack the data for. Jytte Klausen's book contributes to the ongoing scholarly attempt to correct this "data problem" and adds in other welcome ways to a variety of debates currently under way in the study of terrorism, as well as policy and law enforcement. It is likely to remain a key text for many years to come.»

Amarnath Amarasingam, Queen's University, Times Literary Supplment

«Yet a new book provides a stark reminder of the persistence of terrorist networks despite over 20 years of relentless counterterrorism. In Western Jihadism: A Thirty Year History, Jytte Klausen, a professor at Brandeis University and a highly respected scholar of terrorism, traces the origins of al Qaeda and the broader jihadi movement, and how the seeds they scattered throughout the West flourished in the 1990s and even in the post-9/11 era. What emerges is a portrait of a robust movement that, despite having suffered numerous setbacks, has learned from its mistakes, become more connected, and adapted its tactics and structures to keep the flame of jihad alive.»

Daniel Byman, Georgetown University, Foreign Policy

«... a ground-breaking analysis of a global movement about which we often hear but tend to lack the data for. Jytte Klausen's book contributes to the ongoing scholarly attempt to correct this "data problem" and adds in other welcome ways to a variety of debates currently under way in the study of terrorism, as well as policy and law enforcement. It is likely to remain a key text for many years to come.»

Amarnath Amarasingam , Times Literary Supplement

«... new book provides a stark reminder of the persistence of terrorist networks despite over 20 years of relentless counterterrorism... Klausen's work is far-ranging... the network analysis Klausen employs is valuable...»

Daniel Byman, Foreign Policy

«This is the book that everyone's been waiting for. A detailed, comprehensive, and engagingly written history of jihadist terrorism in the West. It convincingly explains its emergence, evolution, and persistence, and offers a systematic assessment of states' responses. Klausen's book is a must read for students, scholars, and policymakers alike.»

Peter R. Neumann, Professor of Security Studies, King's College London

«Jytte Klausen ably captures the contradictions and complexities behind violent jihadism in Western democracies. She stresses transnational organization and strategy rather than local grievances, providing ample empirical evidence to support a highly persuasive argument.»

Martha Crenshaw, Senior Fellow at the Freeman Spogli Institute for International Studies, Stanford U

«Western Jihadism: A Thirty-Year History is among the most important books published on terrorism in years. Jytte Klausen impressively employs a range of methodologies to authoritatively map the historical trajectory of both al Qaeda and ISIS and, critically, of their respective networks as well. The result is a highly original, brilliantly researched, and magisterially argued work that enhances appreciably our knowledge and understanding of this movement—and the continuing threat that it poses.»

Professor Bruce Hoffman, Georgetown University and author, Inside Terrorism

«Klausen's Western Jihadism: A Thirty-Year History not only helps connect the dots that were missed about al-Qaeda's network leading up to the 9/11 attacks, but also then helps piece together the networks that re-emerged and were created in the attack's aftermath. Backed by an unprecedenteddatabase of all Western residents and citizens involved in the jihadi movement, Klausen clarifies many misconceptions and misunderstandings about al-Qaeda's and later the Islamic State's networks in the West and how they have evolved over the past thirty years. It will no doubt become an important resource for academics, practitioners, and policy-makers alike when trying to understand the phenomenon of jihadism in the West.»

Aaron Zelin, author of Your Sons Are At Your Service: Tunisia's Missionaries of Jihad

«The development and evolution of jihadi groups in the West is examined here in forensic detail... it lends readers a deeper and broader understanding of the scale of jihadi networks; their aims; and modus operandi.»

Suzanne Raine, Engelsberg Ideas

«Combining contemporary history, statistical analysis, and gripping anecdotes, Jytte Klausen reveals the driving forces behind Muslim radicalization in the West. This long-awaited book offers an accessible, comprehensive, and data-informed analysis of western jihadism; it is an essential read for specialists, students, government analysts, and policy-makers seeking to make sense of the radicalization puzzle.»

Mohammed M. Hafez, Professor in the Department of National Security Affairs, Naval Postgraduate Scho

«Western Jihadism: A Thirty-Year History is a substantial contribution to the field and to an understanding of the depth of the terrorist networks and their linkages within the networks that remain a global threat today. Professor Klausen's immense data collection and analysis will provide a basis for the study of Western Jihadism for decades to come.»

Gale A Mattox, Professor of Political Science, U.S. Naval Academy

«In the teeming field of Al Qaeda studies Jytte Klausen's book is a real gem; a full history of AQ that really explains why it has, and will continue to have, such staying power. Its analysis is based on a 15-year terrorism data programme that is simply the best I have seen. Though it may be uncomfortable reading for those who prefer to believe that western society itself creates Al Qaeda terrorism, Klausen's conclusions are impossible to dodge.»

Michael Clarke, Professor of Defence Studies, University of Exeter, and Chairman, Countering Jihadis