Pentagon Welcome Defense Secretary James N. Mattis walks with Ukrainian Defense Minister Stepan Poltorak into the Pentagon, Feb. 2, 2018. DoD photo by Army Sgt. Amber I. Smith SHARE IMAGE: Download Image: Full Size (1.41 MB) Tags: European Security, James N. Mattis, SecDef Photo By: Amber I. Smith VIRIN: 180202-D-SV709-0369Y.JPG Photo Gallery