A US soldier puts a blanket on a detainee during a mission in southeast Afghanistan in 2004. American troops went to fight in Afghanistan following the Sept. 11 terrorist attacks. The combat mission, code-named Operation Enduring Freedom, lasted for 13 years until being
brought to an end in December 2014. Thousands of American troops are still in the country, however, as part of the NATO effort to train and advise Afghan security forces. Some US forces are also carrying out counterterrorism missions in the country.
In this image taken from video, US President George W. Bush addresses the nation from the White House on October 7, 2001. He announced that US and British forces had begun airstrikes on Taliban and al Qaeda targets in Afghanistan. The United States linked the Sept. 11 attacks to al Qaeda, a group that operated under the protection of the Taliban regime in Afghanistan. The military operation was launched to stop the Taliban from providing a safe haven to al Qaeda and to stop al Qaeda's use of Afghanistan as a base for terrorist activities.
Al Qaeda leader Osama bin Laden is seen at an undisclosed location in this television image broadcast on October 7, 2001. Bin Laden praised God for the Sept. 11 attacks and swore America "will never dream of security" until "the infidel's armies leave the land of Muhammad."
Soldiers with the Afghan Northern Alliance ride in a truck on October 19, 2001. They were opposition forces allied with the United States in its fight against the Taliban.
An aerial photo, released by the US Department of Defense on October 31, 2001, shows damage to a reported terrorist training camp in Afghanistan. US planes bombed the Taliban front line north of the Afghan capital of Kabul.
US Defense Secretary Donald Rumsfeld, right, speaks to the press during a Pentagon briefing on November 6, 2001. Rumsfeld said the United States had more than doubled the number of its troops based in Afghanistan. Other countries also contributed troops to the coalition.
Afghan refugees reach for bags of rice and sugar being handed out by a local aid organization near Chaman, Pakistan, on December 4, 2001. Tens of thousands of Afghans had crossed the border since the 9/11 attacks.
Al Qaeda prisoners are held in Agom, Afghanistan, on December 17, 2001. Afghan militia leaders declared victory in the battle of Tora Bora and claimed to have captured al Qaeda's last base.
A Northern Alliance fighter bursts into laughter as US planes strike a Taliban position near Tora Bora, Afghanistan, in December 2001.
A detainee is escorted by military police at the US naval base in Guantanamo Bay, Cuba, on February 6, 2002. The base's detention facilities had been repurposed to hold detainees from the US "war on terror."
Mullah Mohammed Omar, the man credited with creating the Taliban, is seen in this photo that spread in 2002. The Afghan government said in a news release that he died in Pakistan in 2013. The White House confirmed his death in 2015 but said "the exact circumstances of his death remain uncertain."
Mohboba, 7, stands near a bullet-ridden wall in Kabul as she waits to be seen at a health clinic on March 1, 2002. She had a skin ailment that plagued many poverty-stricken children in Afghanistan.
Damage is seen in Bamiyan, Afghanistan, where the Taliban destroyed the Buddhas of Bamiyan, the two tallest standing Buddhas in the world. The act generated an outcry in the international community. The Taliban also destroyed villages and towns in Bamiyan Province.
Afghan girls watch United Nations workers unload ballot kits ahead of the country's first democratic election in October 2004. Hamid Karzai was sworn in as President in December.
Afghan women walk past a portrait of Karzai in Kabul on October 26, 2004. Karzai had been in a leadership role since December 2001, when an interim government was formed after the Taliban lost its last major stronghold.
An Afghan soldier provides security near the site where a US helicopter crashed in Ghazni, Afghanistan, on April 7, 2005. At least 16 people were killed.
Protesters in Kabul rally against US President George W. Bush on May 12, 2005.
Poppy farmer Abdul Rassod looks over his field in Panshar, Afghanistan, on May 29, 2005. Afghanistan is the world's largest producer of opium and heroin.
Several people were killed in Kabul after a pair of suicide bombings on November 14, 2005.
Bush and Karzai attend a news conference in Kabul on March 1, 2006. It was Bush's first visit to Afghanistan.
US soldiers disembark from a helicopter in Afghanistan's Ghazni Province on May 28, 2007.
Supplies are dropped to US troops in Ghazni Province on May 29, 2007.
Afghan students recite Islamic prayers at an outdoor classroom in the remote Wakhan Corridor on September 2, 2007.
Troops wait to fire artillery on a Taliban position in Afghanistan's Kunar Province on October 22, 2008.
Bush speaks to US troops during an unannounced visit to Bagram Air Base on December 15, 2008. It was his second and last visit to Afghanistan as President.
US soldiers take defensive positions after receiving fire from Taliban positions in Afghanistan's Kunar Province on May 11, 2009. Army Spc. Zachary Boyd, left, was wearing "I love NY" boxer shorts after rushing from his sleeping quarters to join his fellow platoon members.
Afghan men cast their votes at a polling station in Kabul on August 20, 2009. It was the country's second election.
US Marines make their way up a mountainside in Afghanistan's Helmand Province on August 22, 2009.
Marines pay their respects to Lance Cpl. Joshua Bernard during his memorial service in Helmand Province on August 27, 2009. Bernard was killed during a Taliban ambush earlier that month.
US soldiers fire mortars from a base in Afghanistan's Kunar Province on October 24, 2009.
Afghan President Hamid Karzai prepares to kiss a copy of the Quran during his swearing-in ceremony on November 19, 2009. He won a second term after Foreign Minister Abdullah Abdullah dropped out of a runoff.
US President Barack Obama addresses troops at Bagram Air Base on March 28, 2010. A few months earlier, he announced a surge of 30,000 additional troops. This new deployment would bring the US total to almost 100,000 troops, in addition to 40,000 NATO troops.
US soldiers shield themselves from dust as a helicopter takes off in Afghanistan's Arghandab Valley on July 30, 2010.
Obama and members of his national security team monitor the mission against Osama bin Laden on May 1, 2011. Bin Laden was killed when Navy SEALs conducted a raid at a compound in Pakistan. (Editor's note: The classified document in front of Hillary Clinton was obscured by the White House.)
Obama announces the death of bin Laden on May 1, 2011.
Obama shakes the prosthetic hand of Army Sgt. 1st Class Leroy Arthur Petry on July 12, 2011. Petry was at the White House to receive the Medal of Honor. The Army Ranger lost his hand while tossing an enemy grenade away from fellow soldiers in Afghanistan.
A coalition helicopter fires flares in Kuz Kunar, Afghanistan, on July 17, 2011.
An Afghan soldier carries his wounded colleague to a US Army helicopter after a roadside bomb attack on the outskirts of Kandahar, Afghanistan, on July 29, 2011.
A US Army carry team moves the remains of Sgt. William B. Gross Paniagua at Dover Air Force Base in Delaware on August 1, 2011. Gross Paniagua died in Afghanistan on July 31, 2011, from injuries sustained by an improvised explosive device.
US Army Gen. John Campbell, left, and Command Sgt. Maj. Delbert Byers open the "Resolute Support" flag during a ceremony in Kabul on December 28, 2014. The United States and NATO formally ended the combat mission in Afghanistan. Resolute Support was the name of the new mission to assist and train Afghanistan's troops.