The Crimean Peninsula was annexed by the Russian Federation in February–March 2014 and since then has been administered as two Russian federal subjects—the Republic of Crimea and the federal city of Sevastopol.[38] The annexation from Ukraine followed a Russian military intervention in Crimea that took place in the aftermath of the 2014 Ukrainian revolution and was part of wider unrest across southern and eastern Ukraine.[39][40]

On 22–23 February 2014, Russian president Vladimir Putin convened an all-night meeting with security service chiefs to discuss the extrication of the deposed Ukrainian president, Viktor Yanukovych. At the end of the meeting Putin remarked that “we must start working on returning Crimea to Russia”.[4] On 23 February, pro-Russian demonstrations were held in the Crimean city of Sevastopol. On 27 February, masked Russian troops without insignia[7] took over the Supreme Council (parliament) of Crimea,[41][42] and captured strategic sites across Crimea, which led to the installation of the pro-Russian Aksyonov government in Crimea, the conducting of the Crimean status referendum and the declaration of Crimea’s independence on 16 March 2014.[43][44] Russia formally incorporated Crimea as two federal subjects of the Russian Federation with effect from 18 March 2014.[45]

Ukraine and many world leaders condemned the annexation and consider it to be a violation of international law and Russian-signed agreements safeguarding the territorial integrity of Ukraine, including the Belavezha Accords establishing the Commonwealth of Independent States in 1991, the Helsinki Accords, the Budapest Memorandum on Security Assurances of 1994 and the Treaty on friendship, cooperation and partnership between the Russian Federation and Ukraine.[46][47] It led to the other members of the then G8 suspending Russia from the group,[48] then introducing the first round of sanctions against the country. The United Nations General Assembly also rejected the vote and annexation, adopting a non-binding resolution affirming the “territorial integrity of Ukraine within its internationally recognised borders”.[49][50] The UN resolution also “underscores that the referendum having no validity, cannot form the basis for any alteration of the status of [Crimea]” and calls upon all States and international organizations not to recognize or to imply the recognition of Russia’s annexation. In 2016, UN General Assembly reaffirmed non-recognition of the annexation and condemned “the temporary occupation of part of the territory of Ukraine—the Autonomous Republic of Crimea and the city of Sevastopol”.[51][52]

The Russian Federation opposes the “annexation” label,[53] with Putin defending the referendum as complying with the principle of self-determination of peoples.[54][55] In July 2015, Russian prime minister Dmitry Medvedev said that Crimea had been fully integrated into Russia.