This compendium explores how international law deals with this so-called new warfare from the rise in global terrorism, to insurgency and counter-insurgency campaigns, to the resurgence or mercenaries and the privatization of the use of force. Though many of these phenomena are not new per se (terrorism, insurgency, and other asymmetric tactics have long been in use) their predominance within 21st century conflict over the state-on-state, regular warfare that the laws of war were designed for has created new dilemmas for regulating war. Efforts of state actors to deal with these 21st century threats have equally challenged the basic premises of the laws of war. While many have called for a revamp of existing laws of war, a decade after the September 11 attacks there still remains little consensus on how international law should deal with 21st century threats. This book explores some of the critiques of the laws of war framework, suggestions for reform, and existing gray areas that persist in the regulation of armed conflict.