Understanding the legal and political arguments around Russia's invasion — I'll gather the competing justifications and international assessments.
Russia launched a full-scale invasion of Ukraine on February 24, 2022, calling it a "special military operation." Whether it is justified is contested and depends on which legal and political framework is applied.
Russian government claims its actions are justified on several grounds:
•Denazifying and demilitarising Ukraine and ensuring its neutral status were cited as among the main reasons for the full-scale invasion
•Protecting the residents of the self-proclaimed separatist entities in Eastern Ukraine from alleged genocide and imposing the use of the Russian language
•Halting NATO expansion, which it sees as a direct threat to its borders, and reasserting its sphere of influence over Ukraine
•Other stated rationales include preventing NATO's expansion and demilitarising and "denazify[ing]" Ukraine
Russia specifically accused Ukraine of committing genocide against Russian speakers in the Donbas region and used that claim to justify the invasion. It also argued it was invited to intervene after recognizing the Donetsk People's Republic and Luhansk People's Republic as independent and signing mutual assistance treaties with them.
Arguments against justification under international law:
•The prohibition of the use of force by one state against another is foundational and is articulated in Article 2(4) of the United Nations Charter, which prohibits "the threat or use of force against the territorial integrity or political independence of any state"
•Exceptions to this rule are extremely limited. Article 51 permits self-defence only in response to an armed attack, and Chapter VII authorizes collective action through the UN Security Council. Analysis concluded neither exception applied to Russia's invasion: Ukraine did not launch an armed attack against Russia, and the Security Council did not authorize force, making it a unilateral and illegal use of force
•Humanitarian intervention is not a legally recognized exception to the prohibition on the use of force, and no credible international organization or observer, including the United Nations, found evidence of genocide in Ukraine
•Russia's invasion is described as a clear violation of the United Nations Charter and an act of aggression that is a crime under international law
•Russia's claims of genocide have been widely rejected as baseless. Putin's accusation that Ukraine was committing genocide in the Donbas have been widely rejected as baseless by other countries and international organizations. When Ukraine brought a case to the International Court of Justice (ICJ), the Court ordered Russia to suspend its invasion on March 16, 2022, and found no substantiation for the genocide claims
•Self-defence arguments based on NATO expansion have been rejected by legal scholars because the right to self-defence under Article 51 only arises in response to an actual or imminent armed attack, and vague threats or political discomfort do not meet that threshold
International response:
•The United Nations General Assembly approved a nonbinding resolution condemning Russia for invading Ukraine and demanding that it withdraw its military forces
•The vote passed 141 to 5, calling on Russia to pull its troops out of Ukraine. The resolution deplored "in the strongest terms the aggression by the Russian Federation against Ukraine" in violation of the UN Charter.
In summary, Russia argues the invasion was a preemptive and protective measure for security and for Russian-speaking populations, while Ukraine, most UN member states, the ICJ, and major international legal bodies consider the invasion a violation of the UN Charter's prohibition on the use of force and therefore unjustified under contemporary international law.