At the end of World War II Austria, Germany and Berlin were divided into four zones. In 1955, a treaty was signed. The treaty said that the Allied forces must leave Austria. In return, the Austrian government promised to do certain things, like not form a territorial union with Germany and recognise certain minorities, amongst others. The whole of Europe was separated into a Soviet Union zone in the East and a neutral or US-dominated zone in the West. The splitting of Europe, Germany and especially Berlin into two political blocks was part of the Cold War between the United States of America and other western countries on one side and the Soviet Union and its allies on the other. The wartime Allied Forces split after their common enemy, Nazi Germany, was defeated in May 1945.