PENTAGON GREETING U.S. Defense Secretary Robert M. Gates, right, and U.K. Defense Secretary Liam Fox, left, enter the Pentagon with U.S. Navy Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, back left, and Gen. Sir David Richards, U.K. chief of Defense Staff, April 26, 2011. SHARE: Download: Full Size (0.06 MB) Credit: VIRIN: 605047-F-APV61-373.jpg Photo Gallery