Germany annexed Austria in 1938 , and soon turned its attention to its eastern neighbors . Roosevelt made it clear that , in the event of German aggression against Czechoslovakia , the U.S. would remain neutral . After completion of the Munich Agreement and the execution of Kristallnacht , American public opinion turned against Germany , and Roosevelt began preparing for a possible war with Germany . Relying on an interventionist political coalition of Southern Democrats and business-oriented Republicans , Roosevelt oversaw the expansion U.S. airpower and war production capacity
Kristallnacht
Kristallnacht
Franklin D. Roosevelt