Germany
1941
Nazi Germany Attacked them.
Germany broke the Non-Agression pact with the Soviet Union and attacked them therefore Soviets joined the allies to fight Germany.
The Nazi Party of Germany attacked the USSR on June 22, 1941.
They attacked the Soviet Union - Operation Barbarossa.
It attacked Poland from the east as part of the nazi-soviet pact.
When they were attacked by Germany. Very bad choice for Germany.
germany and soviet union
The Soviet Union had a non-aggression pact with Germany so they took over the eastern part of Poland, partly to keep an anti-communist government, as Germany was, as far from the Russian border as possible.
Germany attacked several major cities in the Soviet Union during World War II. Among the cities attacked were Moscow, Stalingrad, and Leningrad.
The Soviet Union attacked Poland on September 16 1939