In his defense speech of Mundt, the East German defense attorney (played by George Voskovec) states "Smiley was indeed Leamas's friend. He was also a planner in the section called Satellites Four, which operates behind the Iron Curtain." The term "Iron Curtain" would not have been used by officials of East Germany or other Soviet bloc countries to refer to the east-west divide. Originally created by Winston Churchill, the phrase "behind the Iron Curtain" became a disparaging characterization of the east bloc countries and their socialist systems. It was seen as serving to keep people in and information out, and people mostly throughout the West used the metaphor in that context. See more
Our work, as I understand it, is based on a single assumption that the West is never going to be the aggressor. Thus, we do disagreeable things, but we're defensive. Our policies are peaceful, but our methods can't afford to be less ruthless than those of the opposition, can they? You know, I'd say, uh... since the war, our methods - our techniques, that is - and those of the Communists, have become very much the same. Yes. I mean, occasionally... we have to do wicked things. Very wicked things...