Answer:
The "iron curtain," a term coined by Prime Minister Churchill, was usually used to describe the line drawn between the democratic, capitalist countries in Western Europe and the Soviet-controlled, communist countries in Eastern Europe. This line was also important for containment theory because the capitalist powers of the world did not want communism to spread past the iron curtain.
This "curtain" made it difficult for nations in Eastern Europe to create democratic governments. The Soviet Union used military force to stop people from creating democracy beyond the iron curtain. Additionally, they could not advance their economies because the USSR controlled most trade in Eastern Europe and forced communism on all of the countries, even if they did not want it.