The global policy of the free countries had to be changed in the Ante Cold War and especially in the Interbellum  even if at that time it was difficult to imagine this term to characterize an open period. This point was important because the notion of satellite state was present in the mind of Soviet Union before the official creation of the so-called Iron Curtain. Even at that time false flag operations were committed with the intent of disguising the real source of responsibility and blaming another party. This kind of fear was dominant not only after the World War I but also after the Great Depression. Because everyone was suspected for doing strange things that would explain the situation. An attack from the Soviet Union became an obsession for the three countries. This was the main reason of the creation of a network of countries able to protect themselves. The notion of Interbellum became even more natural even if the US adopted a non-interventionist foreign policy from 1932 to 1938. Everything showed that the World War II was inevitable. This was the end of the Interbellum.