Sovetskaya Litva found itself free at the same time as the fall of Supreme Soviet of the Lithuanian SSR, what change allowed both of the actions to happen?
Supreme Soviet of the Lithuanian SSR The Supreme Soviet of the Lithuanian SSR (Lithuanian: "Lietuvos TSR Aukščiausioji Taryba" ; Russian: Верховный Совет Литовской ССР , "Verkhovnyy Sovet Litovskoy SSR") was the supreme soviet (main legislative institution) of the Lithuanian SSR, one of the republics comprising the Soviet Union. The Supreme Soviet was established in August 1940 when the People's Seimas declared itself the provisional Supreme Soviet. According to the constitution it was very similar to modern democratic parliaments: it was elected every four (later five) years and had the power to create, amend and ratify the constitution, laws, and treaties and appoint officials in the Council of Ministers (the executive branch). However, in reality the elections were staged, the Soviet had very little actual power and carried out orders given by the Communist Party of Lithuania (CPL). The situation changed in 1988, when the Lithuanians began seeking independence from the Soviet Union. The political power shifted from CPL to the Soviet, which adopted a number of important constitutional amendments and laws, paving the way for the independence. The first free elections were held in February 1990 and were won by pro-independence Sąjūdis. During its first session the Supreme Soviet adopted the Act of the Re-Establishment of the State of Lithuania and renamed itself the Supreme Council of the Republic of Lithuania.
Polish–Lithuanian War The Polish–Lithuanian War was an armed conflict between newly independent Lithuania and Poland in the aftermath of World War I. The conflict primarily concerned territorial control of the Vilnius Region, including Vilnius, and the Suwałki Region, including the towns of Suwałki, Augustów, and Sejny. The conflict was largely shaped by the progress in the Polish–Soviet War and international efforts to mediate at the Conference of Ambassadors and later the League of Nations. There are major differences in Polish and Lithuanian historiography regarding treatment of the war. According to Lithuanian historians, the war was part of the Lithuanian Wars of Independence and spanned from spring 1919 to November 1920. According to Poland, the war included only fighting over the Suwałki Region in September–October 1920 and was part of the Polish–Soviet War.