why did American suddenly need to develop the national security policies

Discussion Questions: Considering the new in which American found itself in the post-WWII era (i.e., one of the two dominant powers in a new bipolar period), why did American suddenly need to develop the national security policies (e.g., Containment) and processes (e.g., DIMEFIL, PMESII, etc.) it had never had or needed previously?

Instructions

Your initial post must address at least two concepts (three is even better!), be of sufficient length to address the discussion prompt sufficiently and contain sufficient substance to be meaningful (a good guide is for it to be around 300 words), and it must include some type of attribution to the lesson material (doing so for at least two of the sources is sufficient to demonstrate mastery). To fully satisfy this , your initial post should include direct references to at least two of the assigned readings and provide complete citations for them at the bottom of your post