My answer to What are the best information sources for determining the US government's plans for starting specific …
Answer by Ken Larson:
The U.S. develops many contingency plans for warfare. All respond to geopolitical and physical threats posed by countries, terrorism and events.
All are highly classified in the plans and operations venues of the Pentagon and the intelligence agencies.
The best way as a citizen or interested observer to view your question is to historically research the careers of Generals Eisenhower and Schwarzkopf. Both were put in charge of planning in detail large scale contingency operations at the Pentagon targeted at specific threats. They were ultimately put in charge of the operations when the threats became reality. (Eisenhower – WWII in Europe and Schwarzkopf the First Gulf War)
The above model still exists today in the Pentagon for plans and operations. Technology has added a few new risks and threats, such as terrorism and cyber warfare but those elements have simply been folded into the model.