The article focuses on the role of the Russian-Ukrainian war, which began in 2014 in a hybrid format and continues as a full-scale invasion from February 24, 2022, as a key factor in the formation of a new European and world security architecture. It is noted that the historical origins of the war go back to the Middle Ages and are related to the cultural, mental, worldview differences between Ukrainians and Russians, and are also the result of the imperial-chauvinist ambitions of Russia/USSR. As for the political aspects of the Russian-Ukrainian war, since the beginning of the 1990s, Russia sought to revive the USSR, which took various forms, from economic wars and information propaganda to outright military aggression. Such markers in relation to Ukraine are the events in Crimea in 1992-1994, related to the division of the Black Sea Fleet and the "Meshkovshchyna", the situation around the island of Tuzla during 2003-2005, the propaganda and ideological occupation of Donetsk and Luhansk regions with the active involvement of pro-Russian Ukrainian political elite.