The Soviet occupation of the Baltic states covers the period from the SovietBaltic mutual assistance pacts in 1939, to their invasion and annexation in 1940, to the mass deportations of 1941.

In September and October 1939 the Soviet government compelled the much smaller Baltic states to conclude mutual assistance pacts which gave the Soviets the right to establish military bases there. Following invasion by the Red Army in the summer of 1940, Soviet authorities compelled the Baltic governments to resign. The presidents of Estonia and Latvia were imprisoned and later died in Siberia. Under Soviet supervision, new puppet communist governments and fellow travelers arranged rigged elections with falsified results. Shortly thereafter, the newly elected "people's assemblies" passed resolutions requesting admission into the Soviet Union. In June 1941 the new Soviet governments carried out mass deportations of "enemies of the people". Consequently, at first many Balts greeted the Germans as liberators when they occupied the area a week later.

The Baltic states or the Baltic countries is a modern unofficial geopolitical term, typically used to group three countries: Estonia, Latvia and Lithuania. All three countries are members of NATO, the European Union, the eurozone, and the OECD. The three sovereign states on the eastern coast of the Baltic Sea are sometimes referred to as the "Baltic nations", less often and in historical circumstances also as the "Baltic republics", the "Baltic lands", or simply the Baltics.

All three Baltic countries are classified as high-income economies by the World Bank and maintain a very high Human Development Index. The three governments engage in intergovernmental and parliamentary cooperation. There is also frequent cooperation in foreign and security policy, defence, energy, and transportation.The term "Baltic states" ("countries", "nations", or similar) (Estonian: Balti riigid, Baltimaad; Latvian: Baltijas valstis; Lithuanian: Baltijos valstybės) cannot be used unambiguously in the context of cultural areas, national identity, or language. While the majority of the population both in Latvia and Lithuania are indeed Baltic peoples (Latvians and Lithuanians), the majority in Estonia (Estonians) are culturally and linguistically Finnic.