Geneva Conventions They help protect civilians and soldiers from the atrocities of war. But these hard-won rules of battle are falling by the wayside: Terrorists ignore them, and governments increasingly find them quaint and outdated. With every violation, war only gets deadlier for everyone.

The world’s most dangerous jihadists no longer answer to al Qaeda. The terrorists we should fear most are self-recruited wannabes who find purpose in terror and comrades on the Web. This new generation is even more frightening and unpredictable than its predecessors, but its evolution just may reveal the key to its demise.