A former federation of 15 republics occupying the northern half of Asia and part of Eastern Europe, comprising Russia, Belorussia (Belarus), Ukraine, the Baltic States (Estonia, Latvia, and Lithuania), Georgia, Armenia, Moldova (Moldavia), Azerbaijan, Kazakhstan, Kirghizia, Turkmenistan, Tajikistan, and Uzbekistan. Created as a Communist state after the 1917 revolution, the Soviet Union was the largest country in the world. Its agricultural and industrial production were increased, often by brutal means, until the devastation caused by World War II. In the post-war era it emerged as one of the two antagonistic superpowers, rivalling the USA, in the polarization of the Communist and non-Communist worlds. Attempts to reform its centrally planned economy during the 1980s led to a rise in nationalist feeling and unrest in the republics and some began to secede from the Union, which was finally dissolved in 1991.