** FILE ** Afghan officials investigate the site of a deadly suicide attack on a joint NATO-Afghan base in the Ghani Khail district of Nangarhar province, east of Jalalabad, Afghanistan, Saturday, Jan. 4, 2014. (AP Photo/Rahmat Gul)
U.S. soldiers and service members with the NATO-led International Security Assistance Force (ISAF) attend a religious ceremony on Christmas Eve at Bagram military base in Kabul, Afghanistan, Tuesday Dec. 24, 2013. (AP Photo/Rahmat Gul)