Churchill's speech took place in the United States on March 5, 1946. His speech was very important because he announced the starting of the Cold War. The Iron Curtain was a imaginary line separating Europe into two areas.
The Truman Doctrine was a policy made by President Truman that stated the U.S. would provide political, military and economic assistance in democratic nations.
The NATO pact was formed to defend the communist Soviet Union. The Warsaw pact was the alliance between the Soviet Union and Eastern Europe. The NATO and Warsaw were the two main sides in the war.