El 9/11 y la consecuente guerra contra el terrorismo liderada por Estados Unidos movilizaron a la comunidad internacional con el fin de legitimar intervenciones militares y cambios de regimenes politicos. Sin embargo, los procedimientos del sistema internacional permitieron una adaptacion de las organizaciones terroristas, siendo el caso del levantamiento del Estado Islamico de Irak y Siria a partir de la debilidad institucional iraqui —ocasionada por la intervencion norteamericana de 2003— y la guerra civil siria. Lo anterior exige una revaluacion de los metodos politicos y militares de la lucha contra el terrorismo. Este fenomeno ha activado credos compartidos por diferentes sociedades que exigen disponer recursos de los estados buscando garantizar la seguridad, dando paso a una colectividad social internacional. A continuacion se estudiara al terrorismo como catalizador de la administracion del miedo, la identificacion de amenazas, la busqueda de la seguridad y su consecucion a traves de recursos politicos y juridicos internacionales que cobran legitimidad frente a una opinion publica mundial. De este modo, el terrorismo determina la existencia y orienta el comportamiento de una colectividad social internacional que sobrepasa incontestablemente al estado moderno. Se apelara a un dialogo entre el Derecho Internacional y el constructivismo en los estudios internacionales. The 9/11 terrorist attacks and the subsequent US-lead war against terrorism, called up the international community aiming to legitimize military interventions and political regime changes. However, international system procedures allowed the adjustment and maintenance of terrorist organizations. Such is the case of the Islamic State of Iraq and Syria, which rose up from the Iraqi institutional weakness —due to the 2003 American military intervention— and the Syrian civil war. The aforementioned requires a reappraisal of the political and military methods in the struggle against terrorism. This phenomenon has pushed on a series of shared beliefs by different societies which demand state resources —such as political and legal ones— intended to guarantee security. So, an “international social collectivity” is constituted. The article will study terrorism as a trigger of management of fear, the identification of threats, the pursuit and reach of security through international political and legal resources which, at the same time, gain legitimacy facing a world public opinion. Thereby, terrorism determines the existence and guides the behaviour of an international social collectivity which undeniably overtakes the modern state. The article will develop an analysis between International Law and constructivism in International Studies.