The chapter describes how the UN Charter prohibits the threat or use of force against the territorial integrity or political independence of any state and the role that the Security Council has in this context. It explains how the General Assembly in the context of the aggression against Ukraine has met in an emergency session, adopted resolutions, condemned the invasion of Ukraine, deplored Russia's aggression, and demanded that Russia immediately cease its use of force against Ukraine and withdraw all of its military forces from the territory of Ukraine. The resolutions were adopted by a great majority of the UN Members, which is crucial as a permanent member of the Security Council is committing the violations of the Charter. The chapter also analyses the case referred to the International Court of Justice by Ukraine, the three cases pending before the International Criminal Court and the independent Commission of Inquiry established by the UN Human Rights Council in March 2022. The major challenge with the ICC arrest warrants is to apprehend the suspects. Although the proposal for a special court for the crime of aggression against Ukraine seeks to address the most serious violations committed, it also raises questions about selectivity in international justice. The aggression against Ukraine will have significant effects for the future world order. It is imperative that the international community acts when a permanent member of the UN Security Council is committing flagrant violations of the most basic rules of the Charter of the United Nations.