In this book the experts of the National Institute for Strategic Studies of Ukraine present the unprecedented study of the phenomenon of the world hybrid war, which manifested itself in the Russian aggression against Ukraine. The nature of the hybrid war was analyzed in the context of the global security crisis and was studied as a new type of global confrontation. This research is a complex analysis of the causes and preconditions of the Russian aggression against Ukraine, its strategic goals and specific aspects of conduct in various dimensions including military, political, economic, social, humanitarian, and informational. The authors also analyze the local success of Ukraine in resisting the hostile plans of the Russian Federation in certain spheres. The conclusion of the study is that Ukraine as a state managed to prove its capability of fighting against the aggressor for its sovereignty. The reformation of international security institutions and attainment of balance of power in the new hybrid reality are also analyzed in the research.