Chairman of the Joint Chiefs of Staff U.S. Army Gen. Martin E. Dempsey switches off his microphone while appearing before the Senate Armed Services Committee Sept. 16, 2014, at the Hart Senate Office Building in Washington, D.C. During his testimony, Dempsey discussed U.S. policy toward Iraq and Syria and the threat posed by extremists known as the Islamic State in Iraq and the Levant. (DoD photo by Mass Communication Specialist 1st Class Daniel Hinton, U.S. Navy/Released)