Editor's Note: The United States has been at war since 9/11, but the nature of the enemy remains unclear. Some would say the war is against terrorists of all stripes, while others focus more narrowly on ...

Editor’s Note: The conquest of Mosul and other cities in Iraq by the Islamic State in Iraq and Syria (ISIS) has alarmed the United States and its allies and electrified the Sunni jihadist community. On M...

Editor's Note: The war in Syria has attracted volunteers to fight from around the world, including from the United States. Although senior U.S. officials have warned of this threat, the legal foundation ...