The names of the Crimean annexation vary. In Ukraine, the annexation is known as the temporary occupation of the Autonomous Republic of Crimea and Sevastopol by Russia (Ukrainian: тимчасова окупація Автономної Республіки Крим і Севастополя Росією, romanized: tymchasova okupatsiia Avtonomnoi Respubliky Krym i Sevastopolia Rosiieiu), the illegal occupation of the Autonomous Republic of Crimea, the fall of Crimea, and the invasion of Crimea.
In the Russian Federation, it is also known as the accession of Crimea to the Russian Federation (Russian: присоединение Крыма к Российской Федерации, romanized: prisoyedineniye Kryma k Rossiyskoy Federatsii), the return of Crimea (Russian: возвращение Крыма, romanized: vozvrashcheniye Kryma), and the reunification of Crimea.

Crimea was part of the Crimean Khanate from 1441 until it was annexed by the Russian Empire in 1783 by a decree of Catherine the Great.

After the downfall of Russian empire in 1917 during the first stages of the Russian Civil War there were a series of short-lived independent governments (Crimean People's Republic, Crimean Regional Government, Crimean SSR). They were followed by White Russian governments (General Command of the Armed Forces of South Russia and later South Russian Government).

In October 1921, the Bolshevik Russian SFSR gained control of the peninsula and instituted the Crimean Autonomous Soviet Socialist Republic as a member of Russian Federation. In the following year Crimea joined the Soviet Union as a part of Russia (the RSFSR).

After the Second World War and the 1944 deportation of all of the indigenous Crimean Tatars by the Soviet government, the Crimean ASSR was stripped of its autonomy in 1946 and downgraded to the status of an oblast of the Russian SFSR. In 1954, the Crimean Oblast was transferred from the Russian SFSR to the Ukrainian SSR by decree of the Presidium of the Supreme Soviet of the Soviet Union to commemorate the 300th anniversary of Ukraine's union with Russia. In 1989, under Gorbachev's perestroika, the Supreme Soviet declared that the deportation of the Crimean Tatars under Stalin had been illegal and the mostly Muslim ethnic group was allowed to return to Crimea.

In 1990, the Soviet of the Crimean Oblast proposed the restoration of the Crimean ASSR. The oblast conducted a referendum in 1991, which asked whether Crimea should be elevated into a signatory of the New Union Treaty (that is, become a union republic on its own). By that time, though, the dissolution of the Soviet Union was well underway. The Crimean ASSR was restored for less than a year as part of Ukrainian SSR before the restoration of Ukrainian independence. Newly independent Ukraine maintained Crimea's autonomous status, while the Supreme Council of Crimea affirmed the peninsula's "sovereignty" as a part of Ukraine.

The confrontation between the government of Ukraine and Crimea deteriorated between 1992 and 1995. In May 1992 the regional parliament declared an independent "Crimean republic." In June 1992, the parties reached a compromise, that Crimea would have considerable autonomy but remain part of Ukraine. Yuri Meshkov, a leader of the Russian movement was elected President of Crimea in 1994 and his party won a majo…

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The February 2014 revolution of Dignity that ousted Ukrainian president Viktor Yanukovych sparked a political crisis in Crimea, which initially manifested as demonstrations against the new interim Ukrainian government, but rapidly escalated. In January 2014, the Sevastopol city council had already called for formation of "people's militia" units to "ensure firm defence" of the city from "extremism".

On February 20 several buses with Crimean license plates were stopped at a pro-Maidan checkpoint in a town in Cherkasy oblast. Their passengers were violently intimidated and some buses were burned. This incident was subsequently used by Russian propaganda which made unsubstantiated claims that the passengers were killed in gruesome ways.

The Verkhovna Rada of Crimea members called for an extraordinary meeting on 21 February. In response to Russian separatist sentiment, the Security Service of Ukraine (SBU) said that it would "use severe measures to prevent any action taken against diminishing the territorial integrity and sovereignty of Ukraine". The party with the largest number of seats in the Crimean parliament (80 of 100), the Party of Regions of Ukrainian president Viktor Yanukovych, did not discuss Crimean secession, and were supportive of an agreement between President Yanukovych and Euromaidan activists to end the unrest that was struck on the same day in Kyiv.

Russia was concerned that the new government avowedly committed to closer relations with the West put its strategic positions in Crimea at risk. On 22–23 February , Russian president Vladimir Putin convened an all-night meeting with security services chiefs to discuss extrication of the deposed Ukrainian president, Viktor Yanukovych, and at the end of that meeting Putin had remarked that "we must start working on returning Crimea to Russia". After that GRU and FSB began negotiating deals with local sympathizers to ensure that when the operation began there would be well‑armed "local self‑defense groups" on the streets for support. On 23 February pro-Russian demonstrations were held in the Crimean city of Sevastopol.

Crimean prime minister Anatolii Mohyliov said that his government recognised the new provisional government in Kyiv, and that the Crimean autonomous government would carry out all laws passed by the Ukrainian parliament. In Simferopol, following a pro-Russian demonstration the previous day where protesters had replaced the Ukrainian flag over the parliament with a Russian flag, a pro-Euromaidan rally of between 5,000 and 15,000 was held in support of the new government, and demanding the resignation of the Crimean p…

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