Simi Valley Scene Defense Secretary Dr. Mark T. Esper speaks at the Reagan National Defense Forum, at the Ronald Reagan Presidential Library in Simi Valley, Calif., Dec. 7, 2019. SHARE IMAGE: Download Image: Full Size (2.44 MB) Tags: defense secretary, esper Photo By: David Vergun, DOD VIRIN: 191207-D-UB488-006.JPG Photo Gallery