The article presents a study of legal aspects of the Budapest Memorandum, the only document that Ukraine at the outset of its independence was able to win in exchange for the voluntary abandonment of the nuclear arsenal. While Russia violated its obligations by annexing Crimea and unleashing military aggression, Western “guarantors” fail to counter Russia. An analysis of the BM gives proves that it is a full-fledged legally binding international treaty. Failure of international guarantees of territorial integrity of Ukraine is a destabilizing factor resulting in NP regimes’ erosion because of formation of profound distrust of international guarantees, which in the face of aggression and disregard for international norms demonstrate their helplessness.