Crimea is a peninsula located on the northern coast of the Black Sea. With the collapse of the Soviet Union in 1991, Crimea became part of the newly independent Ukraine, leading to tensions with neighboring Russia.
In 1954, Crimea was transferred to the Ukrainian Soviet Socialist Republic as a symbolic gesture by Soviet leader Nikita Khrushchev. Following the breakup of the Soviet Union in 1991, Crimea became part of the independent Ukraine. Russia's Black Sea Fleet is stationed in Sevastopol and the southern tip of the peninsula continues to be a Russian stronghold in the region. Throughout the last decades tensions between the two neighbors have occasionally flared, but nothing like the escalation and mobilization of troops in March 2014.
Lawmakers in Russia are considering a proposal to condemn Germany's 1990 reunification, labeling it an "annexation" of the East by the West. It's thought to be Moscow's answer to condemnation of its takeover of Crimea.
About 30 people have been killed in the eastern Ukrainian city of Mariupol as fighting escalated to the worst level in months. Pro-Russia separatists had announced they were launching an offensive on the strategic city.