Prelude to the Russian invasion of Ukraine

In March and April 2021, prior to the 2022 Russian invasion of Ukraine, the Russian Armed Forces began massing thousands of personnel and military equipment near Russia's border with Ukraine and in Crimea, representing the largest mobilisation since the illegal annexation of Crimea in 2014. This precipitated an international crisis due to concerns over a potential invasion. Satellite imagery showed movements of armour, missiles, and heavy weaponry towards the border. The troops were partially withdrawn by June 2021, though the infrastructure was left in place. A second build-up began in October 2021, this time with more soldiers and with deployments on new fronts; by December over 100,000 Russian troops were massed around Ukraine on three sides, including Belarus from the north and Crimea from the south. Despite the Russian military build-ups, Russian officials from November 2021 to 20 February 2022 repeatedly denied that Russia had plans to invade Ukraine.

The crisis was related to the War in Donbas, itself part of the Russo-Ukrainian War, ongoing since February 2014. Intercepted phone conversations of Sergey Glazyev, a top advisor to Russian President Vladimir Putin, disclosed the specifics of the project Novorossiya to take over not just Crimea, but also the Donbas, Kharkiv, Odesa, and Zaporizhzhia regions of Ukraine, which Russia apparently aimed to annex following Crimea. The plan involved fomenting widespread unrest using pro-Russian agents on the ground, and then orchestrating uprisings that would announce rigged referendums about joining Russia, similar to the one that took place in Crimea on 16 March 2014. In December 2021, Russia advanced two draft treaties that contained requests for what it referred to as "security guarantees", including a legally binding promise that Ukraine would not join the North Atlantic Treaty Organization (NATO) and a reduction in NATO troops and materiel stationed in Eastern Europe, threatening unspecified military response if those demands were not met in full. NATO rejected these requests, and the United States warned Russia of "swift and severe" economic sanctions should it further invade Ukraine. The crisis was described by many commentators as one of the most intense in Europe since the Cold War.

On 21 February 2022, Russia officially recognised the two breakaway regions in eastern Ukraine, the Donetsk People's Republic and the Luhansk People's Republic, as independent states, and deployed troops to Donbas, in a move interpreted as Russia's effective withdrawal from the Minsk Protocol. The breakaway republics were recognised in the boundaries of their respective Ukrainian oblasts, although much of this territory was still held by Ukrainian government forces. On 22 February, Putin declared the Minsk agreements as invalid and the Federation Council unanimously authorised him to use military force in the territories. On the morning of 24 February, Putin announced that Russia was initiating a "special military operation" in the Donbas, and launched a full-scale invasion into Ukraine.