Three points are addressed in this paper. First, it is claimed that the events of 11 September 2001 mark a significant change in the historical context of Post-Cold-War developments. These changes are summed up as a) the rise of non governmental and non insurrectional organizations such as Al Qaeda as war actors; b) an accentuation of the trend toward the expressivization of war; c) an imperialization of US foreign policy. Second, the possible contribution of sociological analysis to the understanding of terrorism is discussed. Third, some scenarios concerning the future long term impact of the threat of terrorism on complex societies are explored.