What is the ultimate lawful source of military orders?

The National Command Authority is recognized as the ultimate lawful source of military orders because it encompasses the President of the United States and the Secretary of Defense. This dual command structure is crucial because it ensures that all military actions are sanctioned at the highest levels of government, thereby adhering to constitutional and legal frameworks. When the President, as Commander-in-Chief, and the Secretary of Defense issue orders, they are making decisions that are foundational to national security and military operations.

In contrast, while the Secretary of Defense plays a critical role in the execution and management of military orders and policies, their authority is derived from the President. Congressional approval is essential for various aspects of military engagement, particularly regarding budgets and declarations of war, but does not directly issue operational military orders. The Joint Chiefs of Staff assist in advising and planning but do not hold the ultimate decision-making authority when it comes to military commands. Therefore, the National Command Authority holds the highest legal authority in the chain of military command.