Is Russia's invasion of Ukraine justified?

This is a question where I can offer factual context, but I should be clear that whether an action is "justified" involves a moral/political judgment that reasonable people—and international bodies—have weighed in on, and I'll try to give you the relevant facts and the dominant international legal/political consensus rather than just my personal opinion.

International legal consensus:
The invasion, launched by Russia in February 2022, has been assessed by most of the international community as a violation of international law. The UN General Assembly passed resolutions with large majorities (141 countries in the initial 2022 vote) condemning the invasion and demanding Russian withdrawal, on the grounds that it violated Ukraine's sovereignty and territorial integrity under the UN Charter, which prohibits the use of force against another state's territorial integrity except in self-defense or with Security Council authorization.

Russia's stated justifications:
Russia has offered several rationales, including:

Most international legal scholars, Western governments, and the International Court of Justice (in preliminary rulings) have rejected these as legally sufficient justifications for a full-scale invasion, particularly the genocide claims, which the ICJ found unsubstantiated.

Counter-view/context some raise:
Some analysts (a minority view, often called "realist" or geopolitical) argue NATO expansion created legitimate security concerns for Russia, even if they don't consider the invasion itself justified as a response. This is distinct from endorsing the invasion's legality or morality.

My take: Based on the weight of international law, the UN Charter's prohibition on aggression, and the overwhelming international response, the invasion is widely regarded as unjustified and a violation of international law. I don't think there's serious ambiguity on the legal question, even though the geopolitical context leading up to it is more contested among analysts.

If you want, I can go deeper into any specific angle—the legal arguments, NATO expansion debate, war crimes allegations, or how different countries have voted/responded.