190102-D-SV709-0005 Reporters greet Acting Defense Secretary Patrick M. Shanahan as he arrives at the Pentagon, Jan. 1, 2019. Shanahan assumed duty as acting secretary following the departure of former Defense Secretary James N. Mattis. DOD photo by Army Sgt. Amber I. Smith SHARE IMAGE: Download Image: Full Size (3.06 MB) Tags: pat shanahan, first day, Department of Defense, SecDef, Pentagon, Patrick M. Shanahan, dod, arrival, current, Acting Secretary of Defense Photo By: Sgt. Amber Smith VIRIN: 190102-D-SV709-0005.JPG Photo Gallery