Who serves as the principal defense policy advisor to the President?

The Secretary of Defense serves as the principal defense policy advisor to the President. This position is responsible for overseeing the Department of Defense and managing the armed forces. In this role, the Secretary of Defense is tasked with advising the President on military strategy, defense planning, and the allocation of defense resources, making them the key figure when it comes to defense issues at the highest level of government.

The Vice President, while an important part of the administration, typically does not have a central role in direct defense policy, which is primarily the purview of the Secretary of Defense. The National Security Advisor focuses more on overall national security strategy and interagency coordination, rather than being specifically dedicated to defense matters alone. The Secretary of State primarily deals with foreign affairs and diplomacy, making it a different focus than the defense-related responsibilities that the Secretary of Defense holds.