NATO soldiers with the International Security Assistance Force (ISAF) arrive at the site of a suicide attack in Kabul May 16, 2013. (Photo by Mohammad Ismail/Reuters)

An Afghan National Army soldier assigned to the Mobile Strike Force Kandak fires an RPG-7 rocket-propelled grenade launcher during a live-fire exercise supervised by the Marines with the Mobile Strike Force Advisor Team on Camp Shorabak, Helmand province, Afghanistan, on May 20, 2013. (Photo by Staff Sgt. Ezekiel R. KitandweUSMC)

A trailer transports armored vehicles, used by NATO forces during the Afghan war, along a road after their arrival at Port Mohammad Bin Qasim, some 40 km (25 miles) from Karachi, on May 25, 2013. After more than ten year NATO and U.S. have started withdrawal of their equipments from Afghanistan, local media reported. (Photo by Athar Hussain/Reuters)

A Mobile Strike Force Vehicle assigned to the Afghan National Army Mobile Strike Force Kandak, navigates through a series of obstacles at a rough terrain driving course on Camp Bastion, Helmand province, on May 13, 2013. (Photo by Staff Sgt. Ezekiel R. Kitandwe/USMC)

Corpsmen with Combat Logistics Regiment 2, II Marine Logistics Group provide medical care to an Afghan Uniformed Police officer at Combat Outpost Musa Qa'la, on May 18, 2013. The AUP were patrolling through Musa Qa'la District when a roadside IED detonated. The police officer sustained minor injuries to his head and face, caused by shrapnel from the explosion. (Photo by Sgt. Bobby J. Yarbrough/USMC)

Newly graduated Afghan National Army soldiers attend their graduation ceremony at the Kabul Military Training Center in Kabul, on May 23, 2013. (Photo by Omar Sobhani/Reuters)

A team of wrecker operators with Combat Logistics Battalion 6, 2nd Marine Logistics Group, hook a seven-ton truck chassis during vehicle recovery training at Twentynine Palms, California, May 25, 2013. The Marines pulled the chassis from a sandy ravine as part of a training exercise meant to prepare them for possible scenarios they may encounter during their upcoming deployment in support of Operation Enduring Freedom. (Photo by Cpl. Paul Peterson/USMC)

A foreign youth pops an ollie on her skateboard as Afghan youths gather for The Sound Central Festival at the French Cultural Center in Kabul, on May 2, 2013. The Sound Central Festival, now on its second year, is the only event of its kind that takes places in Afghanistan, where music was banned by the Taliban until the end of 2001. (Photo by Massoud Hossaini/AFP Photo)

Moha Zakir, a trainee at the Afghan National Army commando school at Camp Moorehead. (Photo by Staff Sgt. Dustin Payne/USAF)

U.S. Army Spc. Robert Purvis, a generator mechanic with Headquarters Support Company, 3rd Battalion, 7th Infantry Regiment, 4th Infantry Brigade Combat Team, 3rd Infantry Division, skypes with his wife Shandel Purvis, on May 13, 2013, from Forward Operating Base Shank, Afghanistan, as they wait for the birth of their first son at Winn Army Community Hospital, Fort Stewart, Georgia. (Photo by Staff Sgt. Elvis Umanzor/US Army)

An artist paints graffiti on a wall during the Sound Central music festival in Kabul, on May 1, 2013. (Photo by Omar Sobhani/Reuters)

An Afghan National Army commando with 3rd Company, 1st Special Operations Kandak, pulls security on a patrol through a poppy field during a clearing operation in Khugyani district, Nangarhar province, Afghanistan, on May 9, 2013. (Photo by Staff Sgt. Kaily Brown/US Army)

Afghan school children walk home after classes at an open-air classroom on the outskirts of Mihtarlam in Laghman province on May 25, 2013. (Photo by Noorullah Shirzada/AFP Photo)

A young Afghan man jumps from a diving board into a swimming pool on a hill overlooking Kabul, Afghanistan, on May 17, 2013. The swimming pool build by the Soviets more then 30 years ago has rarely been used caught instead in the middle of decades of war. (Photo by Anja Niedringhaus/AP Photo)

An Afghan National Army soldier returns from a patrol through local villages of Hesarak, Nangarhar province, on May 17, 2013. (Photo by Spc. Vang Seng Thao/U.S. Army)

Afghan air force 2nd Lt. Niloofar Rhmani walks the flight line at Shindand Air Base, Afghanistan, prior to her graduation from undergraduate pilot training, on May 13, 2013. Rhmani made history on May 14, when she became the first female to successfully complete undergraduate pilot training and earn the status of pilot in more than 30 years. She will continue her service as she joins the Kabul Air Wing as a Cessna 208 pilot. (Photo by Senior Airman Scott Saldukas/USAF)