Soviet Union invades Finland, beginning the Winter War

Soviet forces crossed the Polish border as the Polish state faced German invasion. Soviet authorities described the move as protecting Ukrainians and Belarusians, while it also extended Soviet control...

The treaty revised the division of occupied Polish territory and formalized spheres of influence. Its confidential protocols show how great-power bargaining over borders overrode the sovereignty of...

The agreement granted the USSR military bases in Latvia. Officially framed as mutual assistance, it constrained Latvian sovereignty and foreshadowed further Soviet pressure on the Baltic states.

The treaty transferred Vilnius to Lithuania but required Soviet military bases on Lithuanian territory. It combined a territorial concession with a powerful strategic foothold that compromised...

The Soviet government accused Finland of shelling Soviet positions and used the incident to intensify the crisis. Finland denied responsibility; the event became a pretext for terminating the...

The League condemned the Soviet invasion of Finland and expelled the USSR. The decision exposed the weakness of collective security and the limits of Soviet claims to defend peace through...

Soviet forces entered Estonia and Latvia after ultimatums and entered Lithuania under a similar demand. The occupation followed the 1939 mutual-assistance pacts; subsequent controlled political...

Following a Soviet ultimatum, Romania withdrew and Soviet troops entered Bessarabia and Northern Bukovina. The move expanded Soviet control and affected Romanian, Ukrainian, Jewish, Russian, and other...

Newly installed assemblies adopted resolutions seeking incorporation. These votes followed Soviet military occupation and political coercion; the Soviet and Baltic accounts of the process remain...

The USSR created the Moldavian SSR from most of Bessarabia and the Moldavian Autonomous SSR, while northern Bukovina and parts of Bessarabia were attached to the Ukrainian SSR. The new borders divided...