The Crimean peninsula, which Russia seized from Ukraine in 2014, is at the centre of the worst East-West standoff since the Cold War.
The fate of Crimea and four provinces where Russia has captured territory since invading Ukraine in 2022 was widely thought to be on the agenda of talks on Tuesday between U.S. President Donald Trump and Russian President Vladimir Putin.
HISTORY
Crimea, which juts out into the Black Sea off southern Ukraine, was absorbed into the Russian empire along with most ethnic Ukrainian territory by Catherine the Great in the 18th century. Russia's Black Sea naval base at Sevastopol was founded soon afterwards.
More than half a million people were killed in the Crimean War of 1853-56 when competing geopolitical powers Russia and the Ottoman Empire, backed by Britain and France, took up arms. The conflict reshaped Europe and paved the way for World War One.
In 1921, the peninsula, then populated mainly by Muslim Tatars, became part of the Soviet Union. The Tatars were deported en masse by Soviet leader Josef Stalin at the end of World War Two for alleged collaboration with the Nazis.
Crimea became part of Russia within the Soviet Union until 1954, when it was handed to Ukraine, also then a Soviet Republic, by Stalin's successor Nikita Khrushchev, a Ukrainian.
After the collapse of the Soviet Union in 1991, there were periodic political tussles over its status between Moscow and Kyiv before Russia captured Crimea by force in 2014.
RUSSIAN SEIZURE OF CRIMEA
Russia sent forces into Crimea and seized control of the peninsula after Ukraine's pro-Russian president, Viktor Yanukovych, was ousted during mass protests in February 2014.
After Crimea voted in a disputed referendum to become part of Russia, Russia formally annexed Crimea on March 18, 2014, with Putin saying Crimea has always been and remains an inseparable part of Russia.
The United Nations General Assembly, the United States and many other countries condemned the annexation, and the U.S. and the European Union imposed sanctions on Russia over its moves. Few countries have recognised Crimea as part of the Russian Federation but the Kremlin has said the question has been closed "forever."
WHAT HAS ZELENSKIY SAID ABOUT CRIMEA?
Ukrainian President Volodymyr Zelenskiy has ruled out ceding territory occupied by Russian forces and has said Ukrainian sovereignty of Crimea must be restored through diplomacy.
MILITARY SIGNIFICANCE
Russia's Black Sea base in Sevastopol, which was leased from Ukraine, gives Moscow access to the Mediterranean.
Russia has frequently used Crimea as a launchpad for missile and drone attacks on Ukraine since sending tens of thousands of troops into the country on February 24, 2022 in what Putin calls a "special military operation". Ukrainian forces have also fired missiles at Crimea since Russia's 2022 invasion.
After its full-scale invasion in 2022, Russia enforced a de facto blockade of Ukraine's Black Sea ports which severely restricted grain exports that had been vital to Kyiv's pre-war economy. This resulted in a rise in world food prices and the threat of famine in lower-income countries. A deal known as the Black Sea Grain Initiative was reached in July 2022 to allow safe passage from certain ports but it later collapsed.
GEOGRAPHY
The mountainous peninsula is attached to the rest of Ukraine by a narrow strip of land in the north. To the east, it is separated from Russia by the narrow Kerch Strait. A bridge built by Russia across the strait has been damaged during the war.
With an area of 27,000 sq km (10,000 sq miles), Crimea is slightly smaller than Belgium, with the city of Simferopol as its capital.
POPULATION
The pre-war population was around 2 million. Ukraine's 2001 census showed around 58% were ethnic Russian, 24% ethnic Ukrainian and 12% Tatars.
ECONOMY
Crimea's temperate climate made it a popular tourist destination for Ukrainians and Russians before the Russia-Ukraine war, especially Yalta, where the Soviet, U.S. and British victors of World War Two met in 1945 to discuss the future shape of Europe.
Before the 2022 invasion, it accounted for 3% of Ukraine's gross domestic product. Wheat, corn and sunflowers are the main crops.
Crimea has chemical processing plants and iron ore is mined in Kerch in eastern Crimea. Ukraine has two grain terminals in Crimea - in Kerch and in Sevastopol.
