I'll examine Russia's stated reasons for the invasion alongside international law and global response.
Russia's 2022 full-scale invasion of Ukraine remains contested, with Russia offering legal and political justifications that are rejected by a large majority of states and international lawyers.
1. Russia's stated justifications
In his 23-24 February 2022 address announcing a "special military operation," President Vladimir Putin claimed:
•Military intervention was necessary to "protect people who have been subjected to abuse and genocide" by the Ukrainian government and to "protect Russia and our people".
•The stated aims included "the demilitarisation and denazification of Ukraine".
Legal justifications advanced by Russia include:
•That its use of force is lawful under Article 51 of the UN Charter, which preserves the right to individual and collective self-defence.
•Claims of individual self defence, collective self defence on behalf of the self proclaimed entities of Donetsk and Luhansk, humanitarian intervention, protection of nationals abroad, and allegations of genocide in eastern Ukraine.
•Specifically, that following formal recognition of the Donetsk and Luhansk People's Republics as independent states in February 2022, both republics requested military aid, and Russia signed mutual defence treaties with these republics. Putin also argued the operation was in execution of treaties of friendship and mutual assistance with the Donetsk and Luhansk People's Republics.
•A geopolitical justification to halt NATO's expansion and push Western military and political influence away from its borders.
•A comparison to interventions by the United States and its allies in Kosovo, Iraq, Libya and Syria as precedent.
2. International law framework
The UN Charter sets out conditions under which member states may legally resort to war or use of armed force, a concept referred to as jus ad bellum.
•Article 2(4) provides that all members "shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state".
•The only two exceptions enshrined in the UN Charter are self-defense under Article 51 and an authorization by the Security Council. Article 51 preserves the inherent right of individual or collective self-defense if an armed attack occurs.
3. Response at the United Nations and by legal experts
•Many experts on international law and foreign affairs have opined that the Russian invasion violated Article 2(4)'s prohibition on the "use of force" against other states and have generally rejected Russia's official legal justifications.
•Scholars described Putin's allegations of genocide and comparison of Ukraine to a Nazi state as baseless.
•In any event, Russia's humanitarian justifications are widely perceived as a pretext, and are unsubstantiated by any evidence that Ukraine has committed acts against Russians in Donetsk and Luhansk that could amount to genocide.
•On collective self-defence, critics argue Russia cannot rely on Article 51 because Ukraine has not threatened or attacked any other nation, and because Donetsk and Luhansk are not recognized as separate states under international law.
•Early comparisons to Western interventions have been dismissed by scholars as irrelevant because "one illegal use of force does not justify another" and would carry little weight in any court of law.
At the United Nations:
•Many countries condemned Russia's actions as unlawful violations of Ukraine's sovereignty and of the UN Charter's prohibition on the use of force.
•Russia vetoed a UN Security Council resolution that would have called for Russia to immediately cease its attack on Ukraine. China, India, and the United Arab Emirates abstained.
•The issue was then taken to the UN General Assembly under the "Uniting for Peace" procedure. On 28 February - 2 March 2022, a UNGA resolution condemning the invasion was passed with an overwhelming 141–5 vote majority, with 35 nations abstaining.
•UN General Assembly Resolution ES-11/1, adopted on March 2, 2022, by 141 countries (5 against, 12 abstentions), is titled "Aggression against Ukraine" and deplored "in the strongest terms the aggression by the Russian Federation against Ukraine in violation of Article 2 (4) of the Charter".
Subsequent General Assembly resolutions ES-11/2 through ES-11/6 and others have continued to condemn the aggression and demand withdrawal.
In summary:
•From Russia's perspective, the operation is presented as lawful collective self-defence under Article 51 at the request of Donetsk and Luhansk, plus protection of Russian speakers from alleged genocide and prevention of a NATO threat.
•From the perspective of the UN General Assembly and the predominant view among international lawyers, the invasion violates Article 2(4), does not meet the criteria for self-defence (no prior armed attack on Russia, and Donetsk/Luhansk not recognized as states capable of invoking collective self-defence), and the genocide/humanitarian claims lack evidence.