The Iron Curtain was the physical boundary dividing Europe into two separate areas from the end of World War II in 1945 until the end of the Cold War in 1991. The term symbolized efforts by the Soviet Union to block itself and its satellite states from open contact with the west and non-Soviet-controlled areas. On the east side of the Iron Curtain were the countries that were connected to or influenced by the Soviet Union. On either side of the Iron Curtain, states developed their own international economic and military alliances:

• Member countries of the Council for Mutual Economic Assistance and the Warsaw Pact, with the Soviet Union as the leading state
• Member countries of the North Atlantic Treaty Organization and with the United States as the leading country