The article analyzes the content and meaning of the concept of international terrorism, as well as the functions of states to ensure the security and effectiveness of counter-terrorism. The study is based on the development of legal mechanisms to prevent terrorism through international law. In recent years, we have seen an international threat to state sovereignty by acts of international terrorism. The political structure and power methods of some states operate in such a way that all counteraction to international terrorism is reduced to minimization. Any civilized society cannot exist without legal support and protection of its citizens. A special task of the state in the field of international terrorism, appears to be the sustainable regulation of relations in modern society, in search of cooperation and compromise in solving global and regional problems, the effective operation of international legal acts. An analysis of doctrinal and normative sources has shown that the causes of modern terrorism lie in both the contradictions between states in defining the term "international terrorism" and the means of preventing terrorism. The findings on the nature of international terrorism suggest that legal mechanisms to counter international terrorism must be adopted in compliance with the doctrine of the rule of law and respect for the protection of citizens' rights, as well as the provisions of international law. Offers the author's answer to the research question on the legal mechanism and causes of ineffective counteraction to international terrorism. The goal of the modern state is to ensure the fullest realization of the rights of citizens against terrorism, by providing at the state and international level ways to ensure and protect them. Problems of international terrorism are addressed in both scientific and academic literature.