Of course it can and will happen again. Can the American people be frightened again by the unknown, will the American people try to create conditions where they might feel safer and so on? Look at the fear expressed on these boards, the dire predications. To have fear and want to remove the fear is part of the human condition and will happen again. Fortunately, in the United States the fear is somewhat controlled and with strong leadership can be short and temporary. The real danger is the leadership uses the fear to create more fear and bingo we can have real problems. Think of what some leaders could have done with that fear. Looking back at that period now in the calm cool of the evening it is hard to understand, but the fear was real, sort of an Elm Street thing but it was a controlled fear, and as soon as the fear receded the camps began to close.
I was in a graduate history class right after the war and one of the assignments was to study that episode and determine the politicial motivations behind the camps and the personal gain that ensued. All done by the use of fear.