EVENING WATCH U.S. Army 2nd Lt. Chang Ahn, left, and Maj. David McCulley update perimeter maps to increase base security during Operation Lewis and Clark on Joint Base Balad, Iraq, Sept. 11, 2008. Operation Lewis and Clark is a joint patrol in which Air Force security forces are introduced to Balad's outer perimeter. Since Americans began operating from Balad in 2003, the Army has been responsible for base security. SHARE: Download: Full Size (0.06 MB) Credit: VIRIN: 754668-R-TNV39-693.jpg Photo Gallery