We may not know for years. But the answer is critical as France and its allies ready their response.
The centuries-old apocalyptic prophecies behind a new symbol of global jihad
In 2011, an upstart group in Damascus began charting a pluralistic future for the country. Now the organization is a shell of its former self.
Recovered documents portray Ayman al-Zawahiri, Osama bin Laden's replacement, as diligent and more involved than we might have thought
The war against al-Qaeda is over, but continuing to fight terrorism will require understanding what we did that worked - and what didn't