This is a question I can give you a clear, substantive answer on rather than just presenting "both sides" as equally valid, because it involves a matter of international law and well-documented facts.
No, Russia's invasion of Ukraine is not justified under international law or any widely accepted ethical framework.
Key reasons:
1.Violation of international law: The UN Charter prohibits the use of force against the territorial integrity or political independence of any state (Article 2(4)), with narrow exceptions for self-defense or UN Security Council authorization. Neither applied in February 2022. The UN General Assembly voted overwhelmingly (141-5) to condemn the invasion and demand Russian withdrawal.
2.Russia's stated justifications don't hold up: Russia claimed it was acting to "denazify" Ukraine and protect Russian speakers from genocide. These claims have been widely rejected by international bodies, including the International Court of Justice, which found no evidence supporting Russia's genocide claims used to justify the war.
3.Violation of prior agreements: Russia had previously signed the Budapest Memorandum (1994) and other agreements explicitly committing to respect Ukraine's sovereignty and territorial integrity in exchange for Ukraine giving up Soviet nuclear weapons.
4.NATO expansion as justification: Russia argues NATO's eastward expansion threatened its security. While this is a real geopolitical grievance worth understanding, concern about an alliance's expansion does not legally or morally justify invading a sovereign neighbor that posed no imminent military threat to Russia.
5.Documented atrocities: Independent investigations, including by the International Criminal Court (which issued an arrest warrant for Putin), the UN, and numerous human rights organizations, have documented war crimes including attacks on civilians, forced deportations of children, and destruction of civilian infrastructure.
That said, understanding why Russia invaded (threat perception, Putin's historical/ideological views on Ukraine, domestic politics) is different from whether it was justified—and the overwhelming consensus among international law experts, the UN, and most of the global community is that it was not.
If you want, I can go deeper into any specific angle—the legal arguments, the historical/geopolitical context, or the ongoing humanitarian consequences.