The Russian invasion of Ukraine violated international law (including the Charter of the United Nations). The invasion has also been called a crime of aggression under international criminal law, and under some countries' domestic criminal codes – including those of Ukraine and Russia – although procedural obstacles exist to prosecutions under these laws.
This article discusses the international and domestic legal provisions Russia is said to have violated, as well as Russia's legal justifications for the invasion and the responses of legal experts to those justifications. The legality of the Russian invasion per se is a distinct subject from whether individual political officials or combatants have engaged in war crimes or crimes against humanity.
Background
Invasion of Crimea and Donbas (2014–2022)
In March 2014, Russia annexed Crimea from Ukraine. Around the same time, protests by pro-Russian separatist groups took place in the Donetsk and Luhansk oblasts of Ukraine, collectively called the Donbas. Russia took advantage of these protests to launch a coordinated political and military campaign against Ukraine. These events led to an ongoing military conflict between Russian-backed separatists and Ukrainian forces in the Donbas, during which the separatist-controlled areas were organized into two quasi-states: the Luhansk People's Republic and Donetsk People's Republic. These self-declared governments were not recognized by any governments other than that of Russia.
Russian military build-up (2021–2022)
Russia's invasion of Ukraine in 2022 was preceded by a massive military buildup. Russia began increasing its military presence near its border with Ukraine in March and April 2021. Although the Russian government repeatedly denied that it intended to invade Ukraine, the US government released intelligence of Russian invasion plans in December 2021, including satellite photographs showing Russian troops and equipment near the Ukrainian border. As these events unfolded, Russian officials accused Ukraine of inciting tensions, Russophobia, and repression of Russian speakers, while also making multiple security demands of Ukraine, NATO, and non-NATO EU allies.
On 21 February 2022, Russian President Vladimir Putin gave a televised speech questioning the legitimacy of Ukraine's statehood and indicating that he intended to immediately recognize the independence of Donetsk and Luhansk.
Start of and justifications for invasion (2022)
On Wednesday evening 23 February, Putin addressed his nation on television announcing a "special military operation" in Ukraine. Putin claimed that Russian military intervention in Ukraine was necessary to "protect people who have been subjected to abuse and genocide" by the Ukrainian government and to "protect Russia and our people." Putin also said that the Donetsk and Luhansk People's Republics—which the Russian government had formally recognized only two days before—had requested assistance in their fight against the Ukrainian government. The stated aims of Russia's "special military operation" included "the demilitarisation and denazification of Ukraine."
Scholars decried Putin's allegations of genocide and comparison of Ukraine to a Nazi state as baseless.
Shortly after Putin's speech, the Ukrainian government reported airstrikes and artillery attacks in Kyiv, Kharkiv, and Dnipro, as well as on the border with Russia. Ukrainian President Volodymyr Zelenskyy declared martial law and called for a general mobilization. The conflict remains ongoing.
International law and the responses at the United Nations
Russia has been a member of the United Nations (UN) since December 1991, when it took over the seat of the defunct Soviet Union. The 1945 UN Charter sets out the conditions under which UN member states may legally resort to war or the use of armed force in general (a concept referred to as jus ad bellum).. In the opinion of at least one writer, the 2022 Russian invasion of Ukraine can be grasped as illegal precisely as it broke and undermined the Charter – arguably one of the most significant documents of international law.