Final answer:
The President of the United States is the Commander in Chief of the U.S. armed forces, a position designated by the U.S. Constitution which places the military under civilian control.
Step-by-step explanation:
The Commander in Chief of the U.S. armed forces is the President of the United States. This role is enshrined in Article 2 of the U.S. Constitution, which also includes the responsibility of the President to oversee the various branches of the military, including the Army, Air Force, Navy, and Marine Corps. The principle of civilian control over the military ensures that even the highest-ranking military officers are subject to the authority of an elected civilian leader.