US must be able to protect their borders. also, because of American communism, the freedom of speech, assembly and press were very limited. The US government also put up the loyalty program so as to dismiss the employees that were suspected to be communists. The FBI headed the spreading of information that brought about the damage to individual members of the Congress. This was done to influence the opinion of the public regarding the threats of the communists.
The suffering, misery and death of million of soldiers led to several Americans developing strong anti-war sentiments, and a rejection of several Wilsonian ideals. They felt that the USA had been drawn into the war by merchants,greedy bankers and British propaganda and nobody seemed to question what would have happened had Germany won the war, beyond the quest to avoid war at all costs.
The response is: changes completely
I know this really isn't an answer but I know Crash Course has a video on it on YouTube.
