General Miller is the Chief Executive Officer of the Academy Research and Development Institute (ARDI), a charitable endowment which supports distinguished academic professorships and cadet research at the U. S. Air Force Academy. 

From 2017 to 2024, he served as the inaugural Helen and Arthur E. Johnson Chair for the Study of the Profession of Arms in the Center for Character and Leadership Development at the Air Force Academy. In that capacity, he studied and taught on the influence of increasingly complex missions and newly contested domains on the nature of the military profession, its place in civil society, and its boundaries and role in future national security. 

General Miller’s last active Air Force position was as the Air Force's deputy chief of staff for strategic plans and programs, leading half-trillion-dollar, five-year program formulation and long-range planning efforts. Over nearly 33 years as an active Airman, he also led planning, policy, and strategy for U.S. Northern Command & NORAD (responsible for homeland defense, civil support, and security cooperation with Mexico and Canada); served as the senior USAF commander on the ground in Afghanistan; commanded the nation's only B-2 bomber wing; directed personnel assignments for 340,000 officer and enlisted Airmen; was defense policy adviser to the U.S. ambassador to NATO, a military fellow at the Council on Foreign Relations in New York, and an analyst and planner at Headquarters US Air Force. He commanded flying units at squadron, group and wing levels and has over 3600 flying hours in T-38, B-1, B-2 and other military and civilian aircraft. 

General Miller was a distinguished graduate of the U.S. Air Force Academy and of the College of Naval Command and Staff, and holds an M.Phil. in International Relations from Oxford University. He is President of the North American chapter of the International Society for Military Ethics, a member of the Council on Foreign Relations, a member of the Arizona State University President’s Flag Officer Advisory Council, a Director of the Association of American Rhodes Scholars, and a past President of the Air Force Historical Foundation. From 2018 to 2021, he was the Presidentially-appointed Chair of the United States Section of the Permanent Joint Board on Defense, US-Canada.