Sens. John McCain, R-Ariz., (left) and Jack Reed, D-R.I., hear testimony on operations against ISIS from Gen. Lloyd Austin. Pablo Martinez Monsivais/AP hide caption
Gen. Martin Dempsey
Joint Chiefs Chairman Gen. Martin Dempsey speaks during the graduation ceremony at the U.S. Military Academy at West Point, N.Y., on May 23. In an interview with NPR, he says he's not surprised by the slow going against the Islamic State, predicting it will be a "long campaign." Mike Groll/AP hide caption
Gen. Martin Dempsey On Iraq: A Fight That Will Take 'Multiple Years'
Defense Secretary Ash Carter testifies on Capitol Hill in Washington earlier this month. In an interview on CNN Sunday, Carter complained that Iraqi forces lacked "the will to fight" the self-declared Islamic State. Manuel Balce Ceneta/AP hide caption
Joint Chiefs Chairman Gen. Martin Dempsey briefs reporters at the Pentagon in September about ongoing operations against Islamic extremists in Syria and Iraq. J. Scott Applewhite/AP hide caption
Members of the anti-war activist group CodePink interrupt a Senate Armed Services Committee hearing with Defense Secretary Chuck Hagel (left) and Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff. J. Scott Applewhite/AP hide caption
Joint Chiefs Chairman Gen. Martin Dempsey speaks during a news conference at the Pentagon in December. Manuel Balce Ceneta/AP hide caption
In Iraq, Coordination With Iran Not Impossible, Gen. Dempsey Says
Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, talking to U.S. military personnel in Tokyo last April. Kyodo/Landov hide caption
Gen. Martin Dempsey on Syria
Gen. Martin E. Dempsey, Chairman of Joint Chiefs of Staff, in November of 2013. Paul J. Richards/AFP/Getty Images hide caption
Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey, Secretary of State John Kerry, and Defense Secretary Chuck Hagel testify before the Senate Foreign Relations Committee on Tuesday. Mark Wilson/Getty Images hide caption
A Protester Interrupts
Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey. Win McNamee/Getty Images hide caption
Aug. 13: At Dover Air Force Base in Delaware, the remains of Marine Lance Cpl. Gregory T. Buckley are carried during a dignified transfer. He was killed in a "green on blue" attack. Mark Wilson/Getty Images hide caption