How did u. s. leaders respond to the threat of soviet expansion in europe

1. world war ll conviced u.s leaders that the policies of isolationism & appeasement had been mistakes 

Just think, why was it effective? -it appeled to critics because it was written well, that made it noticeable to the public including the white population-it was also recognizable to the african americans because it was about their heritage.-it was powerful just keep finding more points and elaborate on them. message me if you need more