Republic of Central Lithuania invaded by the Soviets in summer 1920 and being forcibly incorporated into that state, and only the Polish victory derailed this plan. After the Molotov-Ribbentrop pact and the Soviet invasion of Poland of 1939, Lithuania was given in accordance with the Soviet–Lithuanian Mutual Assistance Treaty Vilnius, and its surroundings up to 30 kilometers, on October 10, 1939. A part of the region was given to the Belarusian SSR. Vilnius very quickly became the capital of Lithuania again. But in 1940, Lithuania was swallowed up by the Soviet Union, forced to become the Lithuanian SSR. Since the restoration of Lithuanian independence
Socialist Party of Lithuania regulated, socially oriented market economy - with the production forces and relations of production the managements goal. Markets in the system - as far as possible, and state regulation - as needed. It considers the principles of state regulation as the best economic development incentive. The LSP ideology was based on the methodology of dialectical materialism, the theory of Marxism and contemporary social science. It believed that Socialists should unambiguously disassociate from Stalinist and totalitarian theories and practice. LSP propagated what it believed to be the new 21st century socialism. Socialist Party of Lithuania Socialist Party of Lithuania () was