The new book by Professor M. Lazarovych contains a brief overview of the Russian-Ukrainian war that has been continuing in Ukraine since 2014. Its main reasons and preconditions, ideological principles and course of combat actions are described. The main stages of the forced annexation of Crimea by Russia, the occupation of separate districts of Donetsk and Luhansk regions, and the massive invasion of the Russian regular military forces to Ukraine were investigated. Moreover, the essence of the Russian hybrid war against the Ukrainian state, its types and ways of its implementation were analyzed. Considerable attention is paid to the processes of the revival of the Ukrainian Army, its victories and defeats, the role of the volunteer movement in strengthening the defense capability of our country. The peculiarities and tendencies of the reaction of the international community in violation of the territorial integrity and sovereignty of Ukraine were generalized, the nature of the policy of the agreements on the Russian Federation was clarified. It was determined that the Russian aggression against Ukraine became possible not only through the establishment of a de focto Nazi regime in Russia headed by V. Putin but also through the overwhelming support of his actions by the vast majority of the Russian citizens. The preliminary consequences and lessons of the Russian-Ukrainian war have been established.