Country music artist Jerrod Niemann performs during the Chairman’s USO Holiday Tour at Morón Air Base, Spain, Dec. 21, 2017. Marine Corps Gen. Joe Dunford, chairman of the Joint Chiefs of Staff, and Army Command Sgt. Maj. John W. Troxell, senior enlisted advisor to the chairman, along with USO entertainers, visited service members who are deployed during the holidays at various locations across Europe and the Middle East. DoD photo by Navy Petty Officer 1st Class Dominique A. Pineiro