The Warsaw Pact, officially the Warsaw Treaty Organization of Friendship, Cooperation, and Mutual Assistance, was an alliance founded in 1955 between Eastern European countries to serve as a military and political unit of contiguous communist nations. While the eight signatories—the Soviet Union, Bulgaria, Hungary, Romania, Czechoslovakia, Albania, Poland, and East Germany—were all communist-led nations, not all communist European nations joined. Notably Yugoslavia, which was led by the iconoclastic Marshal Josip Broz Tito, resisted joining an alliance that was so closely controlled by Soviet authorities. These nations still have close ties economically, despite the fall of communism and the dissolution of the Warsaw Pact.

The term “Iron Curtain” was coined by Winston Churchill in the aftermath of the Second World War. It refers to the “curtain” being pulled over Eastern Europe by the Soviet Union which removed those countries from the global capitalist market and isolated Eastern Europe from Western Europe.

The term “Domino Theory” is the idea that if communism is allowed to exist in one country, it will inevitably spread to the neighboring countries until they all fall “like dominoes.” The fear of the spread of communism and attempts to contain it were part of American foreign policy throughout the Cold War era. The term has since been used more liberally to describe the spread of political revolution from one country to the next, such as recently with ISIS in the Middle East.

During the Cold War years the world was divided into two political and economic ideological camps. The western world was capitalist and largely democratic, whereas much of the eastern world (the Soviet Union, China, parts of South Asia) was communist and largely autocratic. In geographic terminology this is referred to as the “East-west divide.”

Turkey, despite being in Eastern Europe and territorially very close to the Soviet Union, was a staunch ally of the United States and NATO throughout the Cold War. American nuclear warheads were kept on Turkish soil for several years, and the Turkish government served as a useful buffer for the United States between the Soviet Union and the other states of the Middle East.

During the Cold War, Europe was divided into two ideological factions. In the West, the vast majority of states were capitalist and democratic and were led by the United States in an alliance known as the North Atlantic Treaty Organization (NATO). In the East, the majority of states were communist and autocratic and were led by the Soviet Union in an alliance known as the Warsaw Pact.

A country that is nominally independent but is under the influence and sometimes control of another much larger nation is known as a “satellite state.” “Satellite states” were particularly common during the Cold War era as both the Soviet Union and the United States sought to bring as many countries as possible under their spheres of influence.