Player Embed Code: Download Embed Share Chairman’s Office Welcomes New Senior Enlisted Advisor Defense.gov Dec. 13, 2019 | 02:12:00 Army Command Sgt. Maj. John W. Troxell relinquishes responsibility as senior enlisted advisor to the chairman of the Joint Chiefs of Staff to Air Force Command Chief Master Sgt. Ramon Colon-Lopez at a ceremony at the Pentagon, Dec. 13, 2019. Army Gen. Mark A. Milley, chairman of the Joint Chiefs of Staff, will preside. A retirement ceremony for Troxell directly follows.