Prior to the Korean and Vietnam wars a series of documents provided the policy framework for what eventually became the implementation dynamic of US military engagement.  See the "X" article by George Kennan that appeared in "Foreign Affairs" in 1947. This "containment" document has had a remarkable lifespan, much like its author. In early 1950 the National Security Council issued a secret white paper known as NSC Directive #68. These two documents shaped the context of American conduct of the Cold War for the next four decades.