Secretary of Defense Jim Mattis (left), speaks with U.S. Air Force Gen. John. E. Hyten (right), commander of U.S. Strategic Command (USSTRATCOM), upon his arrival at Offutt Air Force Base, Neb., Sept. 13, 2017. During his visit, Secretary Mattis met with USSTRATCOM leadership to discuss strategic deterrence in the 21st century. This was Secretary Mattis’ first visit to USSTRATCOM as Secretary of Defense. One of nine Department of Defense unified combatant commands, USSTRATCOM has global missions assigned through the Unified Command Plan that include strategic deterrence, space operations, cyberspace operations, joint electronic warfare, global strike, missile defense, intelligence, and analysis and targeting. (USSTRATCOM photo by Steve Cunningham)