Anti-Taliban Afghan fighters watch several explosions from U.S. bombings in the Tora Bora mountains in Afghanistan December 16, 2001. (Photo by Erik de Castro/Reuters)

Afghan refugee children look from the window of their shelter in the former Soviet embassy, a huge compound amid the destruction of west Kabul, November 27, 2001. (Photo by Damir Sagolj/Reuters)

A young amputee boy walks through the Eidgah mosque in the city of Kabul December 8, 2001 where the U.N. World Food Programme (WFP) started its biggest ever food distribution in the Afghan capital, handing out sacks of wheat to more than three-quarters of the war-ravaged city's population. (Photo by Peter Andrews/Reuters)

US Marines from Charlie 1/1 of the 15th MEU (Marine Expeditionary Unit) fill sand bags around their light mortar position on the front lines of the US Marine Corps base in southern Afghanistan December 1, 2001 nearby a cardboard sign reminding everyone that the Taliban forces could be anywhere and everywhere. This sign is one of several at an area that Charlie Company named Camp Justice on the perimiter of the larger base. (Photo by Jim Hollander/Reuters)

A U.S. Army 10th Mountain Division soldier from Miami, Florida carves the body count that their mortar team has chalked up on a rock, near the villages of Sherkhankheyl, Marzak and Bobelkiel, March 9, 2002. (Photo by Joe Raedle/Reuters)

Afghans walk down a hill in Kabul April 23, 2007. (Photo by Ahmad Masood/Reuters)

A wounded Canadian soldier from the NATO-led coalition crawls for cover seconds after his position was hit by a Taliban shell fired from an 82-millimeter recoilless rifle during an ambush in Zhari district of Kandahar province, southern Afghanistan, October 23, 2007. One Canadian soldier was lightly wounded and an Afghan National Army soldier was shot in the shoulder during heavy fighting in the volatile Mowz-e-Madad area of Kandahar province. (Photo by Finbarr O'Reilly/Reuters)

A Canadian soldier shakes hands with an Afghan boy during a joint patrol with Afghan National Army troops near Panjwaii village, Kandahar province, southern Afghanistan, July 13, 2007. (Photo by Finbarr O'Reilly/Reuters)

Sgt. William Olas Bee, a U.S. Marine from the 24th Marine Expeditionary Unit, has a close call after Taliban fighters opened fire near Garmsir in Helmand Province of Afghanistan, May 18, 2008. (Photo by Goran Tomasevic/Reuters)

In this picture released exclusively to Reuters on January 17, 2009, Taliban militants are seen with their weapons in an undisclosed location in Afghanistan January 16, 2009. (Photo by Reuters/Stringer)

Afghan men harvest opium in a poppy field in a village in the Golestan district of Farah province, May 5, 2009. (Photo by Goran Tomasevic/Reuters)

Members of a mortar team attached to the U.S. Army's Dagger Company, 2-12 Infantry, 4th Brigade return fire with a 120mm mortar during an attack by militants on Michigan Base in the Pesh Valley in Afghanistan's Kunar Province August 7, 2009. (Photo by Tim Wimborne/Reuters)

A U.S. soldier of 2-12 Infantry 4BCT-4ID Task Force Mountain Warrior takes a break during a night mission near Honaker Miracle camp at the Pesh valley of Kunar Province August 12, 2009. (Photo by Carlos Barria/Reuters)

U.S. marines fire during a Taliban ambush as they carry out an operation to clear an area in Helmand province, October 9, 2009. (Photo by Asmaa Waguih/Reuters)

A victim is taken away from the site of a bomb blast in Kabul December 15, 2009. (Photo by Ahmad Masood/Reuters)

A crowd watches an Afghan National Army Air Corps helicopter carrying President Hamid Karzai during an election rally in Gardez, capital of Paktia province, south of Kabul August 4, 2009. (Photo by Ahmad Masood/Reuters)

U.S. soldiers kneel during a memorial ceremony for Captain Daniel Whitten and Private First Class Zachary Lovejoy from Charlie Company, 4th Brigade combat team,1-508, 82nd Parachute Infantry Regiment at the Remote Sweeney FOB in Zabul province, southern Afghanistan, February 8, 2010. CPT Whitten from Grimes, Iowa, and PFC Lovejoy from Albuquerque, New Mexico, were killed by an IED on February 2. when on patrol in southern Afghanistan. (Photo by Baz Ratner/Reuters)

U.S. Marine Lance Corporal Chris Sanderson, 24, from Flemington, New Jersey shouts as he tries to protect an Afghan man and his child after Taliban fighters opened fire in the town of Marjah, in Nad Ali district, Helmand province, February 13, 2010. (Photo by Goran Tomasevic/Reuters)

A U.S. Army medevac crew member attempts to revive a Marine mortally wounded in an IED (improvised explosion device) blast near the town of Marjah in Helmand province in this picture taken August 22, 2010. (Photo by Bob Strong/Reuters)

An Afghan man is detained by U.S. Marines from the First Battalion, Eighth Marines Bravo Company at their base in Talibjan after a battle against Taliban insurgents in Musa Qala district in southern Afghanistan's Helmand province November 7, 2010. (Photo by Finbarr O'Reilly/Reuters)

Graffiti left behind by Taliban fighters remains on the walls of a compound now used as a command center for the U.S Marine Corps's First Battalion, Eighth Marines at Musa Qala in southern Afghanistan's Helmand province, November 10, 2010. (Photo by Finbarr O'Reilly/Reuters)

A father wipes a tear away from his child's face during a Medevac mission in southern Afghanistan's Helmand province November 13, 2010. The child was injured by an explosion. (Photo by Peter Andrews/Reuters)

A U.S. Army soldier from Alpha troop, 4-73 Cavalry Regiment, 4th Brigade, 82nd Airborne Division checks his gear before a mission in the Maiwand district of Kandahar province, southern Afghanistan April 9, 2012. Picture taken April 9, 2012. (Photo by Baz Ratner/Reuters)

Residents on horse-led carts hurry past burning fuel tankers along the GT Road near Nowshera, located in Pakistan's Khyber-Pakhtunkhwa Province October 7, 2010. Gunmen in Pakistan set fire to up to 40 supply trucks for NATO troops in Afghanistan, police said. (Photo by Adrees Latif/Reuters)

U.S. soldier Nicholas Dickhut from 5-20 infantry Regiment attached to 82nd Airborne points his rifle at a doorway after coming under fire by the Taliban while on patrol in Zharay district in Kandahar province, southern Afghanistan April 26, 2012. (Photo by Baz Ratner/Reuters)

Private First Class Brandon Voris, 19, of Lebanon, Ohio, from the First Battalion Eighth Marines Alpha Company stands in the middle of his camp as a sandstorm hits his remote outpost near Kunjak in southern Afghanistan's Helmand province, October 28, 2010. (Photo by Finbarr O'Reilly/Reuters)

Jake Beaudoin, a U.S. Army Private of 508 BSTB, 4th Brigade Combat Team, 82nd Airborne Division, takes cover during a controlled detonation to clear an area for setting up a check point in Zahri district of Kandahar province, southern Afghanistan May 31, 2012. (Photo by Shamil Zhumatov/Reuters)

Afghan boys play with toy guns on the first day of Eid al-Adha in Jalalabad October 15, 2013. (Photo by Reuters/Parwiz)

Afghan National Army (ANA) soldiers approach a suicide attacker after his vest was defused in Jalalabad province June 30, 2013. Afghan security forces captured a would-be suicide attacker before he blew himself up in Jalalabad on Sunday. (Photo by Reuters/Parwiz)

Paratroopers from Chosen Company of the 3rd Battalion (Airborne), 509th Infantry board a waiting CH-47 Chinook helicopter as they begin a helicopter assault mission at Combat Outpost Herrera in Afghanistan's Paktiya Province July 15, 2012. (Photo by Lucas Jackson/Reuters)

An Afghan National Army (ANA) soldier keeps watch after a helicopter takes off near the landslide site in the Argo district of Badakhshan province May 7, 2014. (Photo by Mohammad Ismail/Reuters)

Afghan National Army soldiers (ANA) take position during a gun battle between Taliban and Afghan army at Nahr-e-Kanjak village at Adraskan district of Herat Province April 3, 2014. (Photo by Omar Sobhani/Reuters)