The nation-state of Belarus is a former member of the United Soviet Socialist Republics (the USSR). It is located in eastern Europe. It is a landlocked country. The neighbouring countries of Belarus are Russia, Ukraine, Poland, Lithuania and Latvia. The capital of Belarus is Minsk. Brest, Grodno, Gomel, Mogilev and Vitebsk are the other important cities of Belarus. The Republic of Belarus is the official name of the country. It was previously a part of several other countries including the Duchy of Polatsk, the Grand Duchy of Lithuania, the Polish-Lithuanian Commonwealth and the Russian Empire. In 1922, the country became a member of the USSR. It was then known as the Soviet Socialist Republic of Byelorussia. The country declared its sovereignty on August 27, 1990 and finally became an independent country on August 25, 1991, after the Soviet Union collapsed. The country is still reeling from the after-effects of the Chernobyl nuclear disaster, which took place in its neighbouring country, Ukraine, in the year 1986.