Why did the Soviet Union pursue the domination of Eastern Europe, including constructing the Berlin Wall?

The Soviet Union tried to dominate Eastern Europe, including constructing the Berlin Wall, in order to spread their political power and influence. After World War II, the Soviet Union and the US emerged as global superpowers with two very different ideas on how a country should be run. The US supported the idea of a capitalist society while the Soviet Union supported a communist society.

To spread this idea of communism and to gain resources, the Soviet Union continued to spread their power and control of countries in Eastern Europe during the Cold War era. This "iron curtain" that developed ensured that communism and the Soviet Union's allies would have the ability to stand against America and its allies, should their be a military conflict between the two countries.