U.S. Marine Corps Cpl. Ben W. Gibson (right), with 2nd Combat Engineer Battalion, 1st Battalion, 5th Marines Regiment, Regimental Combat Team 8, sweeps for explosive devices with a metal detector during a reconnaissance patrol in Sangin, Afghanistan, on April 22, 2011. U.S. Marines conduct reconnaissance patrols to survey the local populace and maintain familiarity with the area of operations.