Elevation of the RSFSR-administered Kazakh and Kirgiz ASSRs into Kazakh and Kirghiz SSRs. March 31, 1940 – in the aftermath of the Winter War, Karelian ASSR and the territories ceded by Finland (Finnish Democratic Republic) were merged into the Karelo-Finnish SSR. Occupation of the Baltic states by the USSR followed by their annexation: August 3, 1940 – Lithuanian SSR was incorporated into the USSR.