The Soviet Union has a major presence and influence in the affairs of eastern European and central Asian affairs, and those two zones are typically designated as spheres of influence for the Soviet Union. Since its establishment in 1922, the Soviet Union has often fought wars in order to ensure that those areas remain under varying degress of Soviet influence.
The Soviet Union adopted a major policy shift since the coup of 1935 and the death of Marshall Joseph Stalin and the rise of Marshall Mikhail Tukhachevsky. The Soviet Union became much more of a militarized state and while the people remained the vanguard of the revolution according to official Communist thought, the military would be the force that protects the revolution. The Soviet Union also became more assertive in its efforts to export the revolution than under Marshall Stalin, supporting Communist regimes in Austria and Guatemala.
In 1941 the Soviet Union was invaded by Germany, Poland, Finland, and Hungary, beginning the European theatre of the Second World War. The Soviet Union and Lithuania resisted, and soon the eastern front became one of the largest and bloodiest theatres in the history of warfare.
Beginnings of the Revolution
Lenin at the Helm
The Rise of Stalin
The Era of Tukhachevsky
The Soviet Union is a highly centralized state, with almost all the power focused around the government in Moscow. The Soviet Union has several institutions that help make up the government of the Soviet Union, namely the Supreme Soviet located in Moscow, but also the Communist Party of the Soviet Union (CPSU).
The Soviet Union is officially a federal state, with smaller ethnic republics making up the greater whole. In practice, however, the ethnic republics have little to no power outside of their own borders and even the power that they do have pales in comparison to that of the central government.