The longest war: Scenes from two decades in Afghanistan

A U.S. Marine Humvee kicks up dust as it crosses a group of Marine LAVs (Light Armored Vehicles) as it leaves on patrol from a Marine base in southern Afghanistan December 2, 2001.

US President Joe Biden wipes his eye as he walks through Arlington National cemetary to honor fallen veterans of the Afghan conflict in Arlington, Virginia. President Joe Biden announced it's "time to end" America's longest war with the unconditional withdrawal of troops from Afghanistan, where they have spent two decades in a bloody, largely fruitless battle against the Taliban.

U.S. Marines scan the northwest perimeter of the American military compound at Afghanistan's Kandahar airport using sophisticated thermal imagery equipment on Jan 14, 2002.

U.S. Army 10th Mountain Division soldier Jorge Avino 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, in Afghanistan, March 2002.

Former US President George W. Bush enters a news conference alongside President Hamid Karzai of Afghanistan during a visit to Kabul, Dec. 15, 2008.

American soldiers wounded in a Taliban ambush are led to a helicopter for evacuation, in the Korengal Valley, in eastern Afghanistan, Oct. 24, 2007.

US Marine Sergeant Anthony Zabala of 1st Combat Engineering Battalion of 2nd Marine Expeditionary Brigade runs to safety as an Improvised Explosive Device (IED) explodes in Garmsir district of Helmand Province on July 13, 2009.

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 2010.

Members of the First Battalion, 87th Infantry shield a wounded soldier from the wash of a helicopter that will evacuate him, in Kunduz, Afghanistan, Sept. 17, 2010.

US soldiers stand over the dead body of insurgent after a suicide attack in Maidan Shar, the capital city of Wardak province south of Kabul on September 8, 2013.

A woman is rushed away from the scene of a suicide car bombing that killed at least eight people and wounded dozens more, outside a hotel in Kabul, Afghanistan, Dec. 15, 2009.

Afghan soldiers rush a wounded police officer to an American helicopter in Afghanistan's Kunar Province, March 11, 2010.

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 2012.

A French soldier of the 8th Artillery Regiment takes part in a joint patrol with U.S and Afghan troops in a village in Kharuti, in the mountains of Wardak Province in Afghanistan, July 2009.

A French sniper looks through his rifle's scope while keeping watch over Qarabagh district, north of Kabul, November 2007.

An Afghan girl peers out from behind a wall at passing U.S. Marines driving inside light armored vehicles down Route 4 outside the Kandahar airport, December 2001.

U.S soldiers blow up a roadside bomb set up by Taliban fighters near the town of Walli Was in Paktika province, near the border with Pakistan, November 2012.

A Canadian army medic examines one of eight children brought to a forward operating base after they fell gravely ill from eating explosive powder at a home in the Panjwai district of Kandahar province, September 2009.

Afghan children look at Canadian soldiers of the NATO-led coalition while they patrol in their compound in the Taliban stronghold of Zhari district in Kandahar province, southern Afghanistan, March 2009.

A U.S. soldier from the 3rd Cavalry Regiment pays his respects during a memorial for Specialist Wyatt Martin and Sergeant First Class Ramon Morris at Bagram Air Field in the Parwan province of Afghanistan, December 2014. Specialist Martin and Sergeant First Class Ramon were killed on December 12th by an improvised explosive device while on patrol near Bagram Air Field.

A rocket fired by U.S. soldiers from Dragon Troop of the 3rd Cavalry Regiment explodes next to a destroyed bus at operating base Gamberi in the Laghman province of Afghanistan, December 2014.

An Italian soldier from NATO cries as he carries a casket which contains the body of one of six Italian soldiers killed in Kabul, during a repatriation ceremony at the Kabul international airport, September 2009.

During a rescue mission by a team from a U.S. Air Force Expeditionary Rescue Squadron, army medics carry a wounded Afghan Army soldier to an evacuation helicopter, in Kandahar province, southern Afghanistan, on Aug. 2, 2010.

A child looks on as military vehicles of 5th Striker Brigades drive past his village on the outskirts of Spin Boldak, about 100 kilometers (63 miles, File) southeast of Kandahar, Afghanistan, on Aug. 6, 2009.

Lance Cpl. Blas Trevino of the 1st Battalion, 5th Marines, shouts out as he is rescued on a medevac helicopter from the U.S. Army's Task Force Lift "Dust Off", Charlie Company 1-214 Aviation Regiment after he got shot in the stomach outside Sangin, in the Helmand Province of southern Afghanistan on June 11, 2011. The Army's 'Dust Off' crew needed two attempts to get him out, as they were fired upon and took five rounds of bullets into the tail of their aircraft.

FILE -- President Barack Obama attends a military briefing during an unannounced visit to Bagram Air Base in Afghanistan, May 25, 2014.

Members of the U.S. Navy carry a comrade wounded by an explosion to a medevac helicopter in Kandahar province in southern Afghanistan October 2, 2010.

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.

Two 500 pound bombs explode at dusk on a Taliban fighting position near Blocking Position one above Kamdesh in Afghanistan's Nuristan Province, June 2012.

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 2007.

In this file photo dust kicks off the ground during an operation by US Army soldiers attached to the 2nd platoon, C-Coy. 1-23 Infantry based at Zangabad foward operating base in Panjwai ditrict after Anti Personnel Obstacle Breaching System -- abbreviated as A-POBS (charges fired by rocket and trigger safe detonation of IED's used to make roadside bombs) -- detonate on a nearby road during a dawn operation at Naja-bien village on September 23, 2012.

U.S. troops from the Nato-led International Security Assistance Force (ISAF) light candles during Christmas Eve celebrations at Bagram Airfield, north of Kabul, December 2014.

American soldiers board a transport helicopter in Kunduz, Afghanistan, March 6, 2011.

American soldiers in full gear ride in a C-17 transport bound for Mazar-i-Sharif, Afghanistan, April 5, 2010.

Former President Donald Trump visits Bagram Air Base in Kabul, Afghanistan, Nov. 28, 2019.