The 9/11 Attacks, 20 Years On

Two decades on, we reflect on the profound impact the 9/11 attacks had on security and global strategy.

World Trace Centre Tribute in Light, New York | Flicker / Dennis Leung

The attacks by the Al-Qa’ida terrorist organisation on the World Trade Centre in New York and the Pentagon on 11 September 2001 were cataclysmic in their effect on the global strategic environment.

After two major wars and a dramatic evolution of the terrorist threat, we mark the 20-year anniversary of 9/11 through a series of events, published analysis and videos.

Event Recordings

Watch the recordings of events hosted in memory of the 9/11 attacks.

Members events
The 9/11 Attacks, Two Decades On with The Rt Hon Tony Blair
The 9/11 Attacks from a Historical Perspective

9.11 Two Decades of Disruption

Dr Karin von Hippel participates in a documentary exploring the impact that the catastrophic 9.11 attacks had on the insurance industry, national security, government policy and on society.

IFTRIP, in collaboration with the US Treasury, presents 9.11: Two Decades of Disruption

Our Reflections

RUSI staff, Trustees and Distinguished Fellows share their thoughts on the impact of the 9/11 attacks, 20 years on.

Dr Karin von Hippel: The Global Consequences of the September 11 Attacks

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Suzanne Raine: Terrorism is a Long-Term Strategic Issue

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Jonathan Evans: September 11 was a Watershed Moment

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Sabin Khan: 9/11 Is A Long-Term Generational Challenge

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Professor Michael Clarke: 9/11 Marked A 'Change of Era'

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Sir Mark Rowley: Tackling Hateful Extremism Requires a Broad Approach

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Tom Keatinge: Financially Disrupting Terrorist Activity Post-9/11
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Commentary & Analysis

Access Commentary articles and external publications commenting on the impact of the 9/11 attacks

Two Decades After 9/11, Let Us Not Forget This is About People
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The British and 9/11: So Near and Yet So Far
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The War Might be Over, but ‘Yesterday’s Problem’ has Not Gone Away
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Ending the '9/11 Era': Multilateralism and the Future of Effective Counter-Terrorism

Twenty years on from the devastating 11 September attacks, RUSI Senior Associate Fellows Eric Rosand (US) and Sabin Khan (UK), experts who have worked at the heart of American and British government efforts to counter terrorism and violent extremism post-9/11 provide commentary - Global Coalition, 9 September, 2021

How the US should reestablish trust with its allies

There are two immediate opportunities to work together again on issues that matter to both the United States and the world - By Douglas Alexander, Boston Globe, September 8, 2021

The RUSI Journal Article Collection

The RUSI Journal has published extensively on the themes of terrorism and countering violent extremism over the past 20 years. We have drawn together a collection of articles that trace how our understanding has evolved since that momentous day in September 2001.

The RUSI Journal Article Collection: The 9/11 Attacks - Two Decades of Countering Violent Extremism

This collection of articles traces our understanding of terrorism and violent extremism since 9/11.

Related projects

Prevention Project

A comprehensive research programme on the effectiveness of preventing and countering violent extremism (P/CVE) projects.

Lessons for Preventing and Countering Violent Extremism: An Evidence-Based Approach