The Republic of Crimea, a part of Ukraine, lies on a peninsula stretching out from the south of Ukraine between the Black Sea and the Sea of Azov.
The Russian Tsars and Soviet elite spent summers on its shores which still attract holidaymakers from Russia.
Crimea was annexed by the Russian Empire during the reign of Catherine The Great in 1783 and remained part of Russia until 1954 when it was transferred to Ukraine under the then Soviet leader Nikita Khrushchev.
The port of Sevastopol is a major naval base and has been home to the Black Sea Fleet since Soviet times. Following the collapse of the USSR, the fleet was divided up between Russia and Ukraine.
The continuing presence of the Russian fleet in Sevastopol has been a focus of tension between Russia and Ukraine. In 2008, Ukraine – then under the pro-Western President Viktor Yuschenko – demanded that Moscow not use the Black Sea Fleet during its conflict with Georgia.
Both countries had agreed to allow the Russian fleet to stay until 2017, but after the election of the pro-Russian Viktor Yanukovych as president in 2010, Ukraine agreed to extend the lease by 25 years beyond 2017, in return for cheaper Russian gas.
Given autonomous republic status within Russia after the Bolshevik revolution, Crimea was occupied by the Nazis in the early 1940s. The Tatars were accused of collaboration by Stalin and deported en masse to Central Asia and Siberia in 1944. Many did not survive.
Only as the Soviet Union collapsed were they allowed to return. By the time over a quarter of a million did so in the early 1990s, it was to an independent Ukraine where they faced very high unemployment and extremely poor housing conditions.
There have been persistent tensions and protests over land rights, and allocation of land to Crimean Tatars remains a highly contentious issue.