The Iron Curtain was a term used to describe the separation between West and East during the Cold War. Eastern countries controlled by the Soviet Union during the Cold War were said to be "behind the Iron Curtain." The phrase was used first by Winston Churchill in a speech at Westminster College, who said
From Stettin in the Baltic to Trieste in the Adriatic, an iron curtain has descended across the continent. Behind that line lie all the capitals of the ancient states of Central and Eastern Europe. Warsaw, Berlin, Prague, Vienna, Budapest, Belgrade, Bucharest and Sofia, all these famous cities and the populations around them lie in what I must call the Soviet sphere, and all are subject in one form or another, not only to Soviet influence but to a very high and, in some cases, increasing measure of control from Moscow.
These countries were controlled by the Soviet Union to the extent that they were considered only satellites of the Soviets. The Soviet Embassy in East Berlin was the largest government building in the city, as all of East Germany was governed from there. It was called an "iron curtain" because it was a closed society. Information to and from the west was tightly controlled; there was little knowledge within the west of events in that area, and vice versa. In a metaphorical sense, the Iron Curtain was them the line between the Republican west and Communist East in Europe.