171221-N-RL456-0164 MAYPORT, Fla. (Dec. 21, 2017) Secretary of Defense Jim Mattis, left, and Rear Adm. Sean Buck, commander of U.S. Forces Southern Command/U.S. 4th Fleet, right, depart the amphibious assault ship USS Iwo Jima (LHD 7) following an all-hands call with Sailors and Marines assigned to commands throughout the Jacksonville, Florida Navy Tri-base area. (U.S. Navy photo by Mass Communication Specialist 2nd Class Hunter S. Harwell/Released)