How did the end of world war ii change american foreign policy?

How did the end of World War II change American Foreign policy?

Chicago style with the sources listed  must cite at least 3 times (rely mostly on MPAFR Ch.5)

3-4 pages long doesn’t have to be the best paper just good overall 

NEED DONE Before the 27th at 11:59pm 

 let me know will pay extra for competition tonight.