The Russian Military intervention in Ukraine was one of the most serious international crises in international relations since the end of the Cold War because it included the threat of a large-scale conflict in Europe, between Russia on the one hand, and the United States of America, the European Union and NATO on the Other hand. The study specifically examines the dimensions, determinants, characteristics, and features of US policy towards the Russian military intervention in Ukraine, and its repercussions on NATO, In its axes, the study focused on the dimensions and developments of the Ukrainian crisis, the strategic importance of Ukraine in the Russian and American perspectives, the determinants of US policy towards the Russian-Ukrainian war, the repercussions of the Ukrainian crisis on NATO, and the expected scenarios for the end of the Russian-Ukrainian war. This article reached several important results using a descriptive-analytical approach; Among other things, the American policy towards Russia's attack on Ukraine is multifaceted and includes diplomatic efforts, preventing further aggression, economic sanctions, military aid to Ukraine, and strengthening NATO's deterrence and defense capabilities in the region. Also, the Russia-Ukraine war restored the coherence of the North Atlantic Treaty in an unprecedented way and made it more coherent than before. This pushed European countries towards more armaments and significantly increased European military spending, prompting neutral countries such as Finland and Sweden to formally apply to join NATO, signifying developments that it is not in the interests of Russia.