The Secretary of Defense (SECDEF) is the principal defense policy advisor to the President. Under the direction of the President, the Secretary exercises authority, direction, and control over the Department of Defense. The Secretary of Defense is not a Joint Chiefs of Staff on steroids. It’s a policy implementation role, final authority, and principal liaison to the president and politicians. The policy office is ultimately the most important office in the Pentagon, Under Secretary of Defense Policy can guide foreign policy through the SECDEF.
Partnerships and training exercises, a show of force, Policy stance toward places like Ukraine are formed in the Policy Office.
Tradition is the civilian leadership of the Pentagon, while the military runs the Pentagon. The real leadership that affects daily lives is and will always be military service members. It’s misleading to think that the political appointees are crossing the burn. They are not. They’re there as a stopgap. The natural state of the military is one in conflict. Civilian leadership is necessary – because it means that the will of the people via the president have an approval or denial role. The largest part of many appointee positions is to sign things. Literally to sign and authorize things. But the intent is that the Pentagon is in line with the President’s agenda, like it or not. Agencies implement the company of the President, who is voted by the people. The SECDEF gets a voice, but the President and his agenda are at the helm.
President-elect Trump has selected (retired) Four-star General James Mattis as his nominee for Secretary of Defense. He’s a solid pick by most measurements of success. He went on to become a four-star general, which means he found a measure of ultimate success in his military career. He seemed to have built a strong reputation and cultivated a high perception. It’s hard to say without doing a thorough review of his commands and who worked for him to know how effective of a leader he might be. With commanders, it’s hard to say who is effective is the modern army. Officers are seldom relieved and often toe the line to move forward. Units are tasked beyond the point to access and make changes other than to implement what needs to be done.