Command over the U.S. Armed Forces is established in the Constitution. The sole power of command is vested in the President by Article II as Commander-in-Chief. The Constitution presumes the existence of "executive Departments" headed by "principal officers", whose appointment mechanism is provided for in the Appointments Clause. This allowance in the Constitution formed the basis for creation of the Department of Defense in 1947 by the National Security Act. The DoD is headed by the Secretary of Defense, who is a civilian and member of the Cabinet. The Defense Secretary is second in the U.S. Armed Forces chain of command, with the exception of the Coast Guard, which is under the Secretary of Homeland Security, and is just below the President and serves as the principal assistant to the President in all defense-related matters. Together, the President and the Secretary of Defense comprise the National Command Authority, which by law is the ultimate lawful source of military orders.
Military law introduces offences not recognised by civilian courts, such as absence without leave (AWOL), desertion, political acts, malingering, behaving disrespectfully, and disobedience (see, for example, Offences against military law in the United Kingdom). Penalties range from a summary reprimand to imprisonment for several years following a court martial. Certain fundamental rights are also restricted or suspended, including the freedom of association (e.g. union organizing) and freedom of speech (speaking to the media). Military personnel in some countries have a right of conscientious objection if they believe an order is immoral or unlawful, or cannot in good conscience carry it out.
The human capital shortage may be worse than the shortage in ships. A report by the Maritime Administration to Congress highlighted the problem. The report “estimates that 11,768 qualified mariners ... are available to crew the Ready Reserve Force ... the estimated demand for mariners [in an emergency] is 13,607.” Given the shortage, those mariners who are available “may have to endure prolonged assignments or tours of duty until the emergency is over,” which will decrease effectiveness, increase errors and — of greatest concern — delay deploying the forces necessary to win a large-scale conflict.
Your ASVAB scores determine what jobs you will qualify for in the military. But before you embarrass yourself in front of active duty service members, know that a job in the Army and the Marine Corps is called an MOS, which is an acronym for Military Occupational Specialty. In the Air Force, jobs are called AFSC – Air Force Specialty Code. In the Navy they are known as an NEC - Navy Enlisted Classification and the Coast Guard, jobs are called ratings, or rate for short.