TerrorismTerrorism is a complex phenomenon, constantly changing forms and methods of criminal behavior, and therefore, in order to counter it, various inter-state associations seek to develop a set of effective measures that would ensure the security of society and the stateState. This is hampered by the peculiarity of legal models within the framework of national legislation and differences in the institutional mechanisms that enable specialized law enforcement agencies to implement measures to reduce the level of terrorist threats. The member states of the Collective Security Treaty OrganizationCollective Security Treaty Organization (CSTO) are striving to develop common legal and organizational approaches to combat terrorist threats based on regional legal instruments. The aim of the study is to identify the objective capabilities of an international regional organizationRegional organization (using the CSTO as an example) to create a unified legal framework and a set of practical measures to combat terrorism on the territory of the participating states. In order to achieve the goal, the following tasks have been set: • To analyze international legal acts regulating counter-terrorism issues concluded within the CSTO; • To compare the normative and legal content of documents regulating the issues of combating terrorism in the national legal systems of the participating countries; • assess the homogeneity of concepts in the legal field of combating manifestations of terrorism and identify nodal points in the array of legislative acts devoted to solving this problem; • actualize the system of measures to counter terrorist activity. The research methods were: comparative-legal approach for the study of the legislation concerning the issues of combating terrorism in the CSTO member statesState. The formal-legal method is used to determine the fundamental legal concepts that formulate the legal content of documents adopted to combat terrorism. The systemic method makes it possible to assess the comprehensiveness of the approaches taken within the CSTO to counter terrorismTerrorism. The results of the study show differences in legal approaches to the definition of the basic concepts of “terrorism”Terrorism and “terrorist activity” among the CSTOCollective Security Treaty Organization members, which affects the effectiveness of their collective efforts, affects the quality of practical activities, and which requires harmonization of legal positions of all CSTO members, as well as the creation of unified organizational structures that can potentially unite political and legal approaches in the context of practical operations to reduce international terrorist threats in the CSTO.