Similarly, the Russian references to “genocide” in Eastern Ukraine to justify its intervention cannot be substantiated and offer no justification for military action under international law. Instead Russia has violated the jus ad bellum regime, the conditions under which States may resort to war or to the use of armed force in general. Its actions constitute an act of aggression breaching the cornerstone legal principle of the prohibition of use of force, laid down in article 2 (4) of the UN Charter.
Apart from the jus ad bellum legal framework, Russia’s invasion raises concerns with respect to the application of jus in bello - the body of International Law related to the conduct of hostilities and the means and methods of warfare. As the military operations are still ongoing, it can only be reiterated at this stage that violations of this body of law may trigger war crimes accusations, whereas the particular provisions of the IV Geneva Convention on belligerent occupation will be of high relevance.
Finally, the displacement of many civilians who may ask for protection in other countries will activate international and regional refugee law.
The dramatic events of the last few days fundamentally challenge the basic premises of the international legal order as we know it; the normative consequences of this military operation remain to be seen.