U.S. Marine Gunnery Sgt. Yancy Genao, 37, of N.Y., with the Marine Medium Tiltrotor Squadron 162 out of the Marine Corps Air Station New River, N.C., signals to a fellow crew member aboard a MV-22 Osprey transport aircraft Tuesday, July 26, 2011 while flying over Helmand province, Afghanistan. (Getty Images)

US troops from the 1st Battalion, 67th Armor Regiment, Task Force Dealers under the International Assistance Force Afghanistan prepare for a patrol in Arghandab district, a former Taliban stronghold, on July 26, 2011. (AFP PHOTO)

US troops from the 1st Battalion, 67th Armor Regiment, Task Force Dealers under the International Assistance Force Afghanistan prepare for a patrol in Arghandab district, a former Taliban stronghold, on July 26, 2011. (AFP/Getty Images)

US troops from the 1st Battalion, 67th Armor Regiment, Task Force Dealers under the International Assistance Force Afghanistan prepare for a patrol in Arghandab district, a former Taliban stronghold, on July 26, 2011. (AFP/Getty Images)

U.S. Marine Sgt. Jared Webb, 25, of Ohio, with the 2nd Battalion 12th Marines based in Kaneohe Bay, Hawaii, scans the horizon while on patrol in northern Kajaki, Helmand province, Afghanistan, Friday, July 29, 2011. (AP Photo/David Goldman)

U.S. Marine Cpl. Abraham Willis, 22, of W. Va., with the 2nd Battalion 12th Marines based in Kaneohe Bay, Hawaii, and his IED detection dog Preacher ride in the back of a wagon as they are shuttled over a bridge for a foot patrol at sunrise in Kajaki, Helmand province, Afghanistan, Friday, July 29, 2011. (AP Photo/David Goldman)

U.S. Marine Sgt. Jared Webb, 25, of Ohio, right, with the 2nd Battalion 12th Marines based in Kaneohe Bay, Hawaii, patrols along a makeshift power line pole in northern Kajaki, Helmand province, Afghanistan, Friday, July 29, 2011. (AP Photo/David Goldman)

Sgt. Joshua Jones, a sniper with Headquarters and Headquarters Company, 2nd Battalion, 8th Infantry Regiment, 2nd Brigade Combat Team, 4th Infantry Division, scans his sector for possible threats. When intelligence is received that suggests a possible attack, the snipers are always ready to scan potential enemy attack positions for possible threats, said Staff Sgt. Shawn Young, sniper section leader for 2nd Bn., 8th Inf. Regt. (U.S. Army photo by Capt. Daniel Bustamante)

A sniper with Headquarters and Headquarters Company, 2nd Battalion, 8th Infantry Regiment, 2nd Brigade Combat Team, 4th Infantry Division observes and reports suspicious activity. Snipers have been critical to the Task Force Talon partnered patrols as they are able to identify suspicious activity and report it to the unit on the ground. (U.S. Army photo by Capt. Daniel Bustamante)