The USSR issued an ultimatum to Lithuania demanding formation of a pro-Soviet government and admission of additional Soviet troops, paving the way for occupation and subsequent annexation procedures.
Lithuania accepted the Soviet ultimatum, after which Soviet forces consolidated control and installed a puppet administration to legitimize incorporation into the USSR.
Following Soviet ultimatums, Red Army forces entered Estonia and Latvia and occupied key cities, ending de facto independence and enabling Moscow-backed regime changes.
The U.S. publicly condemned the Soviet occupation of Estonia, Latvia, and Lithuania and adopted a policy of non-recognition of their annexation, shaping decades of diplomatic practice.
The Supreme Soviet of the USSR accepted petitions from the puppet legislatures and incorporated Lithuania (3 Aug), Latvia (5 Aug), and Estonia (6 Aug) into the Soviet Union.
Soviet security organs carried out large-scale deportations across the Baltics (notably 13–14 June), targeting political and social groups labeled “enemies,” with many sent to prisons and remote settlements.
As German forces withdrew, the Red Army entered Tallinn, marking the start of renewed Soviet rule in Estonia and catalyzing postwar resistance, including Forest Brothers activity.
The USSR launched Operation Priboi, deporting more than 90,000 people from Estonia, Latvia, and Lithuania (25–28 March) to facilitate collectivization and weaken armed and social resistance.
A reform initiative group formed at the Lithuanian Academy of Sciences, becoming Sąjūdis—an organizing center for mass mobilization that evolved from reform support into a leading independence movement.
Estonia’s Supreme Soviet adopted a sovereignty declaration asserting the supremacy of Estonian laws over USSR laws—an early constitutional challenge to Moscow during the Singing Revolution.
About two million people formed a human chain linking Tallinn, Riga, and Vilnius to mark the Molotov–Ribbentrop Pact’s anniversary and publicly demand freedom and national self-determination.
The Congress of People’s Deputies acknowledged the existence of the pact’s secret protocols and declared them legally invalid from the moment of signing, undermining Soviet justifications for the 1940 takeover.
Lithuania’s Supreme Council adopted the Act of the Re-Establishment of the State of Lithuania, asserting legal continuity with the pre-1940 republic and becoming the first Soviet republic to declare independence.
Latvia’s Supreme Soviet adopted the declaration “On the Restoration of Independence of the Republic of Latvia,” launching a transition away from Soviet constitutional order and toward renewed statehood.
Soviet forces attacked key sites in Vilnius, including the TV Tower, killing civilians and injuring many during efforts to overturn Lithuania’s independence drive; the violence galvanized international attention.
Latvians erected and defended barricades in Riga (13–27 January) amid fears of a Soviet crackdown, marking a decisive phase of civic resistance during Latvia’s independence transition.
During the failed Moscow coup attempt, Estonia’s Supreme Council proclaimed the restoration of the Republic of Estonia, formally ending the claimed legality of Soviet occupation.
The USSR’s State Council recognized the independence of Estonia, Latvia, and Lithuania—an official Soviet act that followed the August 1991 coup’s failure and accelerated international recognition.
Baltic States under Soviet Rule (1940–1991)
