Counterterrorism and Homeland Security

Insurgents and violent extremists pose a constantly evolving threat, both in the United States and globally. CSIS research provides strategic thinking on the range of efforts to counter terrorist groups and their methods across the world.

Photo: Trent Nelson/The Salt Lake Tribune/Getty Images

Photo: Trent Nelson/The Salt Lake Tribune/Getty Images

Left-Wing Terrorism and Political Violence in the United States: What the Data Tells Us

The Warfare, Irregular Threats, and Terrorism Program examines the state of political violence, finding left-wing violence has risen in the last decade but from very low levels and still well below historic levels of violence by right-wing and jihadist actors.

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Brief by Daniel Byman and Riley McCabe — September 25, 2025

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Seth G. Jones

Seth G. Jones

President, Defense and Security Department; Harold Brown Chair
Daniel Byman

Daniel Byman

Director, Warfare, Irregular Threats, and Terrorism Program
Riley McCabe

Riley McCabe

Associate Fellow, Warfare, Irregular Threats, and Terrorism Program

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Ideological Trends in U.S. Terrorism

The Warfare, Irregular Threats, and Terrorism Program examines the state of terrorism in the U.S., finding left-wing violence has risen in the last decade but from very low levels and still well below historic levels of violence by right-wing and jihadist actors.

Analysis by Daniel Byman and Riley McCabe — September 26, 2025

Global Terrorism Threat Assessment 2025

Terrorism remains a threat to U.S. citizens, assets, and interests despite the national security community’s decreasing focus on counterterrorism.

Report by Alexander Palmer, Riley McCabe, Daniel Byman, and Skyeler Jackson — March 28, 2025

The Escalating Attacks on Tesla Facilities

Since January 2025, a series of attacks have targeted Tesla facilities and vehicles across the United States, bringing renewed attention to a long-standing debate among policymakers, scholars, and law enforcement over what qualifies as domestic terrorism.

Critical Questions by Riley McCabe — March 20, 2025

Jihadist Terrorism in the United States

Despite the attack in New Orleans, long-term trends suggest that jihadist terrorism in the U.S. is not resurgent. The number of jihadist plots and attacks in the U.S. has been low and the average lethality of attacks has also fallen since the territorial defeat of ISIS. 

Brief by Alexander Palmer, Skyeler Jackson, and Daniel Byman — January 21, 2025

The Truth of the Matter

Trudeau's Dramatic Resignation

What led to Justin Trudeau’s resignation, and what does it mean for Canada’s future? Vincent Rigby unpacks it with insight on this episode of the The Truth of the Matter.

Podcast Episode by H. Andrew Schwartz and Vincent Rigby — January 10, 2025

CSIS the truth of the matter