Defense Testifying Defense Secretary Ash Carter and Marine Corps Gen. Joseph F. Dunford, chairman of the Joint Chiefs of Staff, testify on national security challenges and ongoing military operations at a hearing of the Senate Armed Services Committee in Washington, D.C., Sept. 22, 2016. SHARE: Download: Full Size (2.72 MB) Credit: Navy Petty Officer 2nd Class Dominique A. Pineiro, DOD VIRIN: 160922-D-PB383-016.JPG Photo Gallery