Daniel Nielsen entered Federal service in May 1976 as a Procurement intern at the Navy Aviation Supply Office in Philadelphia, Pennsylvania. In February 1978, he took a position as a Contract Specialist intern at the Naval Air Systems Command in Arlington, Virginia. During his tenure at NAVAIRSYSCOM, he served as the Contracting Officer for Tactical Electronic Warfare Programs, C/MH-53E helicopters, E-2C and C-2A aircraft, F/A-18 Production Programs, and the Joint Strike Fighter program. In August of 2002, Daniel was selected as Deputy Director for Program Acquisition and International Contracting, Office of the Under Secretary of Defense (Acquisition, Technology, and Logistics), and appointed to the Senior Executive Service. He has been awarded the Secretary of Defense Medal for Meritorious Civilian Service, the Department of the Navy Superior Civilian Service Award, two Departments of the Navy Meritorious Civilian Service Awards, the Department of the Navy Procurement Competition Award, and the Secretary of the Navy Career Fellowship.