輜重兵
Coffin then became an intelligence watch commander at the United States Space Command and North American Aerospace Defense Command. In 1999, he joined the United States Army Space and Missile Defense Command (USASMDC) staff as the G-4 (Logistics Officer) and subsequently became commander of the 1st Space Battalion. In 2001, he joined the Army staff as a space and aviation system integrator. He attended the Army War College from 2001 to 2002, receiving a Master of Science (M.S.) degree in Military Security Policy and Strategy, and became Chief of the Space and Missile Defense Division on the Army Staff.