In the collective monograph, prepared by specialists of the National Institute of Strategic Studies, for the first time in domestic and world science, the phenomenon of global hybrid war in the perspective of Russian aggression against Ukraine was investigated in detail. The essence of hybrid war is considered in the context of the systemic crisis of world security, and its phenomenon is considered as a new type of global confrontation. The reasons and prerequisites of Russian aggression against Ukraine, its strategic goals, as well as the peculiarities of conducting a hybrid war in various dimensions: military, political, economic, social, humanitarian, and informational, are considered in detail. The local successes of our state in countering the hostile plans of the Russian Federation in separate directions are analyzed. A general conclusion was made that Ukraine proved its capacity as a state that defends its sovereignty in the fight against the aggressor. The issues of reforming international security institutions and finding a balance of power in the new, hybrid reality are discussed.It is intended for politicians, political analysts, high-ranking civil servants, scientists in the field of security studies. The results of the study will be of interest to educators, representatives of civil society, as well as nationally conscious citizens.