This article is the result of research in the context of the Observatory of Geopolitics and International Security of the School of International Relations of the Military Cadet School General Jose Maria Cordova, whose objective is to generate a permanent analysis of the international reality from geographical and historical frameworks that allow understanding the dynamics of competition and conflict in the international system. The reader will find an analysis of the crisis in Ukraine from a neorealist perspective, with elements of neoclassical geopolitics, emphasizing historical, strategic, national security and military issues, in a re-edition of the classical paradigms of international relations. Thus, the article is composed of a detailed description of the internal political situation in Ukraine that led to the protests known as Euromaidan, the subsequent secessionism and the civil war, in which the historical idea of Novorossiya (New Russia) is determinant to understand Moscow's interventionism in the crisis. Subsequently, the geopolitics of Ukraine and the Black Sea are analyzed and special emphasis is placed on the geoeconomics of gas and its location as a point of confluence of three great civilizations, namely Western, Russian-Orthodox and Turkish-Ottoman. Next, the reader will find the main arguments that differentiate the current strategic competition between Russia and the West in the face of the Cold War, emphasizing that Vladimir Putin's geopolitical logic resembles more that of the former Tsarist empire than that of the Soviet Union. Finally, it analyzes the probabilities of a military escalation of the crisis, identifies possible Russian courses of action and the need for a NATO response in terms of deterrence, which leads to highlighting the fact that the Mutually Assured Deterrence of nuclear weapons remains a fact of life in the international system.