In this July 22, 2010, file photo, U.S. Army troops from the 1st Battalion 320th Alpha Battery, 2nd Brigade of the 101st Airborne Division, duck as an Afghan soldier fires a rocket propelled grenade towards insurgent positions at Combat Outpost Nolen, in the volatile Arghandab Valley, in Kandahar, Afghanistan. (AP Photo/Rodrigo Abd, File)
