Editor's Note: What if most terrorism isn’t really terrorism? In past decades, much of what we call terrorism today would have been seen as insurgent violence, revolutionary war, or civil war: a group li...

The Islamic State opened up a new front when it downed a Russian passenger plane in October over Egypt’s Sinai Peninsula. U.S. and allied attention understandably focuses on the terrorism threat posed by...

Editor's Note: The Islamic State has metastasized beyond Iraq and Syria, establishing so-called “provinces” in many Muslim countries. This spread has alarmed U.S. officials, and Yemen – home of Al Qaeda’...