You are obviously supposed to answer this question by referring to a section of a school book that you've been using in class. If you look back, there'll be a paragraph or two saying 'At the end of WWII, the US realised that ...'. THAT's what your teacher wants you to refer to.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.