Early in the Cold War era, NATO and the Warsaw Pact were created by the United States and The Soviet Union, respectively. They were also referred to as the Western Bloc and the Eastern Bloc. The circumstances of these two blocs were so different that they were essentially two worlds, however, they were not numbered first and second. The onset of the Cold War is marked by Winston Churchill's famous "Iron Curtain" speech. In this speech, Churchill describes the division of the West and East to be so solid that it could be called an iron curtain.