Is Russia's invasion of Ukraine justified?

I need more on the ICJ ruling and Budapest Memorandum.No, Russia's full-scale invasion of Ukraine (launched on 24 February 2022) is not justified under international law, and its primary stated rationales do not hold up to factual scrutiny. This is the overwhelming consensus of the United Nations General Assembly, international courts, legal scholars applying just war theory, and most governments. Russia's security concerns and historical grievances are real factors in the broader conflict and deserve serious analysis, but they do not provide a legal or moral justification for a war of aggression against a sovereign state.[1]

International Law

The UN Charter (Article 2(4)) prohibits the threat or use of force against the territorial integrity or political independence of any state. Russia's invasion is a clear violation. The UN General Assembly has repeatedly condemned it as aggression, demanding immediate Russian withdrawal:

The International Court of Justice (ICJ) issued provisional measures in March 2022 ordering Russia to immediately suspend military operations. In related proceedings under the Genocide Convention (Ukraine v. Russia), the ICJ has jurisdiction over Ukraine's claim that there is no credible evidence of Ukrainian genocide in Donbas (as Russia alleged). Russia has submitted counter-claims, but the core Russian pretext has been rejected by independent monitors.[3]

Russia's actions also violate the 1994 Budapest Memorandum, in which Russia (along with the US and UK) pledged to respect Ukraine's independence, sovereignty, and existing borders, and to refrain from the threat or use of force, in exchange for Ukraine giving up the world's third-largest nuclear arsenal inherited from the Soviet Union. Russia breached this in 2014 (Crimea/Donbas) and 2022.