Belarus is a landlocked country in Eastern Europe, that borders Russia to the north and east, Ukraine to the south, Poland to the west, and Lithuania and Latvia to the north. Its capital is Minsk; other major cities include Brest, Grodno, Gomel, Mogilev and Vitebsk. Until the 20th century, the Belarusians lacked the opportunity to create a distinctive national identity, since the lands of modern-day Belarus belonged to several countries, including the Duchy of Polatsk, the Grand Duchy of Lithuania, the Polish–Lithuanian Commonwealth, and the Russian Empire. After the short-lived Belarusian People's Republic (1918–19), Belarus became a constituent republic of the Soviet Union, the Byelorussian SSR. The final unification of Belarusian lands within its modern borders took place in 1939, when the ethnically Belarusian lands that were part of interwar Poland were annexed by the USSR and attached to the Soviet Belarus. The parliament of the republic declared the sovereignty of Belarus on July 27, 1990, and following the collapse of the Soviet Union, Belarus declared independence on August 25, 1991. Alexander Lukashenko has been the country's president since 1994. Since 1996, Belarus has been negotiating with Russia to unify into a single state called the Union of Russia and Belarus.