Final answer:
The ultimate responsibility for protecting personnel and assets from terrorist attacks lies with the Commander-in-Chief, who is the President of the United States, according to the U.S. Constitution.
Step-by-step explanation:
The protection of personnel and assets from terrorist attacks is ultimately the responsibility of the Commander-in-Chief, who is the President of the United States. According to Article II, Section 2 of the Constitution, the President is designated as the Commander in Chief of the Army and Navy of the United States, and by extension, is responsible for the defense and security of the nation, which includes protection from terrorism. While other members of the chain of command, such as the Secretary of Defense, the Joint Chiefs of Staff, and Unit Commanders, have significant roles in defense and security, the ultimate responsibility lies with the Commander-in-Chief.