Which of the following is NOT a component of the operational chain of command?

The operational chain of command typically includes key figures who play direct roles in military operations and are responsible for making strategic decisions, issuing orders, and overseeing forces. The President, as the Commander-in-Chief, holds ultimate authority over the Armed Forces. The Secretary of Defense is responsible for overseeing the Department of Defense and ensuring that military operations align with national defense strategies. The Combatant Commander leads a specific geographic or functional area of operations and is the principal military advisor to the Secretary of Defense and the President regarding military engagement in their area.

In contrast, the Chief of Staff, while a significant leader within the military structure, typically holds a position focused more on administrative and organizational functions rather than being directly involved in the operational chain of command. This role does not usually entail direct authority over operational military forces as the other options do. Therefore, it does not fit within the traditional operational chain of command used in military structures.