ONE LAST QUESTION Defense Secretary Robert M. Gates calls on a reporter during his final scheduled press briefing at the Pentagon, June 16, 2011. Navy Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, joined Gates, who will retire at the end of the month. SHARE: Download: Full Size (0.05 MB) Credit: VIRIN: 136833-P-DMN67-993.jpg Photo Gallery