Player Embed Code: Download Embed Share Mattis, Dunford Testify Before House Armed Services Committee, Part 1 Defense.gov Oct. 3, 2017 | 01:22:25 Defense Secretary Jim Mattis and Marine Corps Gen. Joe Dunford, chairman of the Joint Chiefs of Staff, testify on the on the U.S. defense strategy in South Asia before the House Armed Services Committee, Oct. 3, 2017.