Twenty years after 9/11, the assessment of the “War on Terror” is mixed : heavy financial and human costs, weakening of Al-Qaeda central and the Islamic State in the Levant, but creation of affiliates in different locations, fatigue of endless wars, etc. The Western powers have never been able to deal with the political problems that persisted after their military successes. A new hierarchy of security challenges seems to have put terrorism in its rightful place : a strategic problem among many others.