To mark its fifth anniversary, Stephen E. Flynn, CFR’s leading national security expert, evaluates the general performance of the Office of Homeland Security.

The air travel system remains one of the most high-profile targets for terrorists. This backgrounder examines efforts to improve aviation security since the 9/11 attacks.

Counterterrorism agencies in the United States proudly point to the lack of a “second 9/11 attack” in response to critics of their methods. Here’s a look at the continuing debate over the proper orga…

Al-Qaeda and Hezbollah are supposedly rival groups on opposite sides of sectarian lines. Yet recent statements from senior al-Qaeda leadership suggest a common enemy may be drawing them together, and…