Treaty on the Creation of the USSR on 30 December 1922 by a conference of delegations from the Russian SFSR, the Transcaucasian SFSR, the Ukrainian SSR and the Byelorussian SSR. The Treaty and the Declaration were confirmed by the 1st Congress of Soviets of the USSR and signed by heads of delegations Mikhail Kalinin, Mikhail Tskhakaya, Mikhail Frunze and Grigory Petrovsky, Aleksandr Chervyakov respectively on December 30, 1922. The treaty provided flexibility to admit new members. Therefore, by 1940 the Soviet Union grew from the founding four republics to 15 republics. On 8 December 1991, Russian, Ukrainian and Belarusian Presidents signed the Belavezha Accords. The agreement declared
Russians in the Baltic states on the basis of the legal continuity of their statehood throughout 1940 – 1991, automatically recognising citizenship according to the principle of "jus sanguinis" for the persons who held citizenship before 16 June 1940 and their descendants. Most of those who had settled on the territory of these republics after their incorporation by the USSR of these states by the USSR in 1940 and their descendants received the right to obtain citizenship through naturalisation procedure, but were not granted citizenship automatically. This policy affected not only ethnic Russians, but also the descendants of those ethnic Estonians and Latvians who emigrated