Change of Responsibility Marine Corps Gen. Joseph F. Dunford Jr., chairman of the Joint Chiefs of Staff, swears in Army Command Sgt. Maj. John W. Troxell as the third senior enlisted advisor to the chairman of the Joint Chiefs of Staff during a change of responsibility ceremony on Joint Base Myer-Henderson Hall, Va., Dec. 11, 2015. DoD photo by Navy Petty Officer 2nd Class Dominique A. Pineiro SHARE IMAGE: Download Image: Full Size (1.15 MB) Photo By: Petty Officer 2nd Class Dominique A. Pineiro VIRIN: 151211-D-TE668-037.JPG Photo Gallery