This is a contested geopolitical question — I'll gather Russia's stated justifications and the international legal response to give you a balanced overview.
Russia's full-scale invasion of Ukraine launched on 24 February 2022 has been justified differently by the parties involved, and whether it is "justified" depends on the legal and political framework used to evaluate it.
Russia's Stated Justifications
In his televised address on 24 February 2022, President Vladimir Putin announced a "special military operation".
He framed it as:
1.Self-defense under Article 51 of the UN Charter - to defend the Russian-speaking territories in eastern Ukraine — the Donetsk People's Republic and Luhansk People's Republic — under Article 51 of the United Nations Charter. He cited the decision of the Federation Council and treaties of friendship with the two entities, which Russia had recognized as independent days earlier, saying "We have been left no other option to protect Russia and our people" and invoking "Article 51 of Part 7 of the UN Charter".
2.Protection from genocide - The stated purpose was to "protect the people" in the predominantly Russian-speaking region of Donbas who, according to Putin, "for eight years now, have been facing humiliation and genocide perpetrated by the Kyiv regime".
3.Demilitarization and denazification - Putin said Russia sought the "demilitarization and denazification" of Ukraine, claiming Ukraine's government were neo-Nazis under Western control.
4.NATO expansion and security threat - Putin spoke about the impossibility of reaching an agreement with NATO and accused the alliance of expanding to the east, stating: "As NATO expands to the east, with every passing year, the situation for our country is getting worse and more dangerous", and that further expansion of NATO infrastructure and military development in Ukraine were "unacceptable". He described Ukraine as becoming an "anti-Russia" state supplied with modern weapons.
He also stated there were no plans to occupy Ukrainian territory and warned of immediate consequences for any country that intervened.
Initially, Putin also ordered forces into eastern Ukraine to perform "peacekeeping functions" pursuant to recognition of the two breakaway regions.
Assessment Under International Law
Most international bodies and international law scholars assess the invasion through the UN Charter:
•Prohibition on use of force: Article 2(4) of the UN Charter prohibits the threat or use of force by member states, noting: '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'. A natural extension is that it is unlawful to acquire territory by force — a principle affirmed by the UN Security Council.
•Exceptions: There are only a couple of exceptions to the prohibition. Article 51 outlines that self-defence is an exception if an armed attack occurs against a Member of the United Nations.
•Application to this case: Legal analyses conclude that "Under no scenario is Russia's armed invasion of Ukraine legal under contemporary international law and norms". Self-defense is described as "the only justification for use of force against another country, according to international law" and found in the UN Charter binding for all 193 UN member countries. Analyses state that "Nothing that Ukraine has done to date could be construed as an 'armed attack' on Russia and justify any Russian claim to self-defense", and that "Even if Putin's false claim that Ukraine is targeting Russian-speakers in eastern Ukraine were true, it would not justify the countrywide attacks".
•Genocide and neo-Nazism claims: Putin's accusation that Ukraine was committing genocide in the Donbas have been widely rejected as baseless by other countries and international organizations. Critics responded that there is no evidence to suggest there is a genocide of Russian-speaking people in the Donbas region. Ukraine brought a case before the International Court of Justice (ICJ) to challenge Russia's claim. The ICJ said it had not seen any evidence of genocide committed by Ukraine. Putin's claim that Ukraine was a neo-Nazi state has been widely rejected, with scholars stating "We strongly reject the Russian government's ... equation of the Ukrainian state with the Nazi regime to justify its unprovoked aggression".
•Article 51 and DPR/LPR: Putin's reference to Article 51 is regarded by a number of lawyers as incorrect because the DPR and LPR were not UN member states and were only recognized as independent by Russia.
•Peacekeeping claim: UN Secretary-General António Guterres said he is 'concerned about the perversion of the concept of peacekeeping ... When troops of one country enter the territory of another country without its consent, they are not impartial peacekeepers. They are not peacekeepers at all'. Countries cannot unilaterally establish peacekeeping forces in other countries without that country's consent.
The UN Secretary-General said Russia's invasion directly conflicts with the United Nations Charter.
International Political Response
The UN General Assembly overwhelmingly voted for resolutions condemning the invasion:
•On 2 March 2022, the General Assembly approved a nonbinding resolution condemning Russia for invading Ukraine and demanding that it withdraw its military forces.
•The resolution demanded that Russia "immediately, completely and unconditionally withdraw all of its military forces from the territory of Ukraine within its internationally recognized borders" with 141 countries voting in favor out of 193 members.
•Only Belarus, Eritrea, North Korea and Syria voted with Russia against the resolution.
Other countries abstained, rather than voting in favor or against.
Summary of Positions
•Russian government position: The operation is a justified act of self-defense, protection of Russian speakers from genocide, prevention of NATO encroachment, and denazification/demilitarization.
•Position of the UN General Assembly majority, NATO, and most international law scholars: The invasion violates Article 2(4) of the UN Charter, does not meet the criteria for self-defense under Article 51, and the factual premises cited (genocide, need for denazification) have not been substantiated by evidence found by international courts and monitoring bodies.
Whether the invasion is considered justified therefore depends on whether one accepts Russia's factual claims and its expansive interpretation of self-defense, or the interpretation of the UN Charter held by the majority of states and the UN's principal organs.
2.[International law issues raised by Russia’s invasion of Ukraine
– Parliament of Australia](https://www.aph.gov.au/About_Parliament/Parliamentary_departments/Parliamentary_Library/Research/FlagPost/2022/March/Russia_Ukraine_and_International_Law)