PRESIDENT'S GREETING President Barack Obama greets Navy Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, and Defense Secretary Leon E. Panetta at the Joint Chiefs of Staff change of responsibility ceremony on Joint Base Myer-Henderson Hall, Va., Sept. 30, 2011. During the ceremony, Mullen retired after 43 years of service, transferring the chairman's responsibilty's to Army Gen. Martin Dempsey. SHARE IMAGE: Download Image: Full Size (0.06 MB) Photo By: VIRIN: 226320-Q-JDZ17-523.jpg Photo Gallery