The lack of balance of power in international relations is conditioned by the fact that covert operations become a significant instrument of contemporary foreign policy. Prohibition of war as an instrument and weakening of diplomacy and economic sanctions because of bipolarity have have made covert operations the first option for achieving national interests of a country abroad. Although covert operations undoubtedly violate the moral and ethical principles of international relations, at the end of the Second World War covert operations were institutionalized and their legal framework determined their actions. Immediately after institutionalization, the great powers led the US embarked on the implementation of covert action around the world. Operation Ajax was the first successful covert action that set a framework for further implementation around the world. In the Cold War period, covert operations became the standard of conduct in international relations. The 21st century has brought changes in the technology field and changed the method of carrying out covert operations, but there is still a need for this foreign policy instrument because of terrorism, organized crime and other post-Cold War threats.