The deepening geopolitical conflict between the West and the Russian Federation, intensified by the war in Ukraine, has caused significant changes in the security environment of the Republic of Serbia and has largely complicated the realization of its national and defense interests. Military neutrality, as an important defense interest and key security commitment, is also conditioned by changes in the security environment of the Republic of Serbia, as well as vital national interests such as the preservation of territorial integrity, the prospect of EU membership, and ensuring energy security. Therefore, the subject of research in this paper represents the relationships of connectivity and conditioning of the military neutrality of the Republic of Serbia, key changes in the security environment caused by the war in Ukraine, and the mentioned vital national interests. The paper starts from the hypothetical stance that changes in the security environment of the Republic of Serbia complicate the realization of the military neutrality policy, especially in relation to the mentioned vital national interests. The analysis of these connections and relationships is based on the theoretical postulates of the realist school of international relations, according to which great powers and other international actors use all available instruments for projecting power and achieving interests in an anarchic system. In changed geopolitical circumstances, the military neutrality policy of the Republic of Serbia, based on balanced cooperation with the parties in the Ukrainian conflict, is becoming increasingly difficult to maintain, as there is a serious "coercive" potential of the mentioned parties, related to the vital national interests of the Republic of Serbia, such as EU membership, preservation of territorial integrity, and energy and economic security of the Serbian state and society. The methodology in the research is based on the analysis of relevant sources and literature.