This article analyzes the legal dimensions of the territorial disputes between the Russian Federation and Ukraine within the framework of contemporary international law. The main objective is to examine the legal legitimacy of Russia’s actions in the annexation of Crimea and its involvement in the eastern regions of Ukraine. The study explores fundamental principles such as the prohibition of the use of force, the preservation of territorial integrity, state sovereignty, and the crime of aggression.
The theoretical framework is based on the interaction between peremptory norms of international law (jus cogens) and the responsibility of states for their violation, grounded in the UN Charter, General Assembly Resolution 3314 (1974), and Article 8 bis of the Rome Statute. The research adopts a descriptive–analytical method, relying on documentary analysis of International Court of Justice judgments, UN resolutions, official statements, and doctrinal works.
Findings indicate that Russia’s conduct in Crimea and eastern Ukraine contradicts the fundamental norms of international law, especially the peremptory prohibition on the use of force and the principle of territorial integrity. The study concludes that no emerging customary rule legitimizes such annexations and emphasizes the need to strengthen international mechanisms to deter aggression and uphold the territorial integrity of states.