Player Embed Code: Download Embed Share DOD Official, Combatant Commanders Testify on National Security Challenges Defense.gov March 7, 2019 | 02:17:00 Kathryn Wheelbarger, acting assistant secretary of defense for international security affairs; Army Gen. Joseph L. Votel, commander of U.S. Central Command; and Marine Corps Gen. Thomas D. Waldhauser, commander of U.S. Africa Command, speak at a House Armed Services Committee hearing on the national security challenges and U.S. military activities in the greater Middle East and Africa, March 7, 2019.