Originally established by Osama bin Laden as a vanguard for worldwide Islamist revolution, al-Qaeda became notorious for the 11 September 2001 terrorist attacks on the United States. In response, the US launched a global “War on Terror” which weakened bin Laden's organization, but which, paradoxically, allowed al-Qaeda to reinvent itself as a decentralized social movement. The terrorist attacks in Madrid and London in 2004 and 2005 sprang from this movement, as did the so-called regional affiliates of al-Qaeda in Saudi Arabia, Iraq, Algeria, and elsewhere. The expansion of al-Qaeda after 2001 backfired though, as the violence that was carried out in its name spiraled out of control and failed to win the support of the Muslim masses. After Osama bin Laden was killed by US Special Forces in 2011, the movement began to openly fragment, as illustrated by the rift between al-Qaeda and the self-proclaimed “Islamic State,” which grew out of al-Qaeda's affiliate group in Iraq, in 2014. Osama bin Laden's vision of creating a unified Muslim front to fight the US and Israel ultimately failed, because his radical anti-imperialist agenda was incompatible with the territorially based goals of revolutionary Islamism.