US forces entered Afghanistan as part of the “war on terror” following the 9/11 terror attacks with the goal to destroy the Al-Qaeda network.
The terror group was blamed for bombing the Twin Towers in New York.
The US also wanted to overthrow the Taliban from Kabul for not handing over Osama bin Laden.
Former US President George Bush's administration vowed a swift and decisive war against the Taliban. But that turned into a protracted and deadly conflict that lasted almost 20 years.
The following is a timeline of events in war and the entry of US forces in Afghanistan.
Oct. 1, 2001: Pakistani President General Pervez Musharraf, in an interview with foreign media, says the days of the Taliban appeared numbered.
Oct. 2: Taliban's Ambassador to Pakistan Mullah Abdul Salam Zaeef at a hastily called news conference in Islamabad appeals to the world to help negotiate the Osama bin Laden issue, saying the Taliban will not surrender bin Laden to the US without concrete evidence of his involvement in terror activities.
Oct 4: Veteran Afghan Mujahideen commander Gulbuddin Hekmatyar warns Pakistan that it will pay a heavy price if it helped in a US attack on Afghanistan.
Oct 5: The US sends 1,000 elite troops to Uzbekistan after the former Soviet republic gave Washington the go-ahead to use an airbase in its anti-terror campaign against neighboring Afghanistan.
Oct. 6: The Taliban militia fire missiles at a suspected American spy plane circling the Afghan capital, Kabul, fueling fears of imminent US military strikes.
Oct. 6: In line with UN resolutions 1276 and 1333 in 1999 and 2000, respectively, Islamabad freezes bank accounts and assets of top Taliban leaders apart from Osama bin Laden and his associates being maintained in Pakistan.
Oct. 7: The US, in concert with Britain, strike at what is described as Al-Qaeda training camps and Taliban command and control facilities in several places in Afghanistan, signaling the start of a military campaign against the Kabul regime and bin Laden.
Oct. 7: The Taliban claim to have shot down a US military plane.
Oct. 7: Bush in a televised speech says the US launched strikes against Al-Qaeda training camps and military installations of the Taliban regime.
Oct. 8: Taliban commanders get to listen to Mulla Omar on wireless sets calling to fight until the end.
Oct. 9: Deputy Foreign Minister Mullah Abdur Rahman Zahid at an emergency meeting of the 56-nation Organization of the Islamic Conference (OIC), appeals to Muslim states to press the US and Britain to halt airstrikes bombing sites in Afghanistan because they are illegal and not approved by the UN.
Oct. 11: The US and British military operations can go on until next summer, British defense chief Michael Boyce says in first indication by the West of how long it expects the campaign to last.
Oct. 11: With hundreds of US troops having arrived in Pakistan, Americans are allowed to use at least two airfields in Sindh and Balochistan against the Taliban.
Oct; 13: Afghan Health Ministry official Maulvi Abdul Malik confirms 473 civilians, including 107 women and 51 children, died in the previous five days following US-led air raids.
Oct. 13: The Pentagon admits US forces inadvertently hit a residential area near the Kabul airport with a 907-kilo bomb after missing a military helicopter that was targeted.
Oct. 14: Pakistan Foreign Minister Abdul Sattar says Afghanistan's King Zahir Shah, who was overthrown in 1973, will be acceptable to Pakistan as head of a broad-based government once the Taliban are ousted.
Oct. 14: Taliban supreme leader Mullah Muhammad Omar says his Islamic militia will teach the United States "a much more bitter lesson" than that was taught to the Soviet Union in the 1980s. In an interview with a Saudi daily, he says: "It's true that we have not started our real battle against the United States because of their technological superiority. But – God willing – we will not greet them with roses," Omar said in a telephone interview from Afghanistan, said the Arabic-language newspaper.
Oct. 19: US Special Forces begin ground operations in small numbers in southern Afghanistan in support of the CIA's effort to break away Taliban factions.
Oct. 19: Mujahideen commander Maulvi Jalaluddin Haqqani says the Taliban have prepared a strategy to start a long guerrilla war from the mountains against any invading troops that seize their cities and a new government that is formed there to wage "a never-ending war to free Afghanistan again from invaders."
Oct 20: US special forces parachute into southern Afghanistan and assault an airfield and a Omar residence near Kandahar in a coordinated raid to seize intelligence material.
Nov. 8: Mohammad Mohaqeq, a member of the Hezb-i-Wahdat party, says US warplanes touched down for the first time at Afghanistan's key Bagram airbase, north of Kabul.
Nov. 13: The Taliban abandoned the Afghan capital without firing a single shot and fled eastwards to their spiritual headquarters of Kandahar.
Nov. 14: Anti-Taliban forces claim victories with hardline Afghan Islamists' final stronghold of Kandahar having fallen as Washington prepares for a "needle in a haystack" hunt for Osama bin Laden.
Nov. 14: Anti-Taliban Northern Alliance leaders seize reins of government in Kabul despite Western calls for broad consultation on a post-Taliban regime.
Nov. 16: Taliban forces begin evacuating the political and spiritual heartland of Kandahar to launch a guerrilla war from Afghanistan mountains. Omar orders pullout to avoid further civilian casualties from US airstrikes against the southern city.
Nov. 19: Taliban leadership hand over control of Farah province to local tribal Shoora (council) following negotiations with elders.
Nov. 21: New Governor of Herat Province, Ismail Khan, voices opposition to the deployment of foreign troops.
Nov. 22: International Committee of the Red Cross says between 400 and 600 bodies have been found in Mazar-i-Sharif following its capture by the Northern Alliance.
Nov. 25: The Taliban's last northern stronghold of Kunduz falls to Northern Alliance forces, Alliance commander Daoud Khan says.
Nov. 25: A Northern Alliance spokesman says up to 700 foreigners killed when they rose up against their captors in northern Kunduz province.
Nov. 28: A senior commander from forces loyal to Gul Agha, former mujahideen governor of Kandahar, says 160 captured Taliban fighters who refused to surrender last week are executed before the eyes of US military personnel.
Nov. 29: Amnesty International calls for an international inquiry into the killing of hundreds of Taliban prisoners at the Qala-i-Jangi fort.
Nov. 30: US-led coalition spokesman ambassador Kenton Keith rejects suggestion made by Amnesty International to hold an inquiry into the killing of hundreds of Taliban prisoners at Qala-i-Jangi.
US forces exit from Afghanistan
Though then-US President Barak expressed a willingness to negotiate with the Taliban for peace in Afghanistan, President Donald Trump took a practical step and pushed Pakistan to release Mullah Abdul Ghani Baradar, who served as the Taliban's second-in-command under Omar and coordinated the group's military operations in southern Afghanistan.
A Taliban spokesman announced Baradar's release from a jail in Karachi, Pakistan, on Oct. 24, 2018, after eight years in detention.
Feb. 29: After more than 18 years of conflict, the US and the Taliban sign an agreement to bring peace to Afghanistan. The accord, which was unanimously adopted by the UN Security Council is supported by China, Pakistan and Russia.
Feb. 29: As part of the Doha Peace Agreement, the US agrees to withdraw military forces within 14 months, which expired in May 2021.
March 1, 2020: Afghan President Ashraf Ghani opposes a condition in the US-Taliban deal requiring his government to release 5,000 Taliban prisoners.
March 10: Ghani orders the release of 1,500 Taliban detainees under US pressure.
Sept. 3: Afghanistan releases 400 Taliban prisoners as stipulated by the US-Taliban deal, paving the way for intra-Afghan peace talks to begin.
Sept. 12: After seven months of delays, Afghanistan government officials and Taliban representatives meet in Qatar for peace talks.
Dec. 2: Afghan government and Taliban negotiators reach an agreement on a framework for peace talks. At the same time, the Taliban maintain its “fight and talk” approach, intensifying the conflict to improve its bargaining leverage with the Afghan government.
April 14, 2021: US President Joe Biden declares that the last American forces in Afghanistan, estimated to be 2,500, will begin departing on May 1. Biden says the entire departure process will be completed by Sept. 11, which marks 20 years after the al-Qaeda attack that prompted the US invasion of Afghanistan.
April 15, 2021: In response to US President Joe Biden’s to defer full withdrawal until Sept. 11, the Taliban issues statement saying that failure to complete the withdrawal by May 1 “opens the way for (the Taliban) to take every necessary countermeasure, hence the American side will be held responsible for all future consequences.”
July 2, 2021: US troops discreetly withdraw from Bagram Airfield, Afghanistan's largest airfield. It effectively ends the US' engagement in the war.
July 9, 2021: US President Joe Biden announces the pullout of US forces from Afghanistan after 20 years of war will take place on Aug. 31, rather than Sept. 11.
Aug. 6: Taliban seize Zaranj, the capital of Nimruz province in the south, becoming the first provincial capital to fall.
Aug. 7: Taliban capture entire northern province of Jawzjan, including its capital, Sheberghan.
Aug. 8: Taliban take control of Sar-e-Pul, the capital of the namesake northern province. Group also take control of Kunduz and Taluqan provinces on same day.
Aug. 9: Aybak, the capital of the northern province of Samangan, is seized by Taliban fighters.
Aug. 10: Taliban capture Farah, the capital of the western province of the same name, and later that day, Pul-e-Khumri, the capital of the central province of Baghlan.
Aug. 11: Taliban seize control of Faizabad, the capital of the northern province of Badakhshan.
Aug. 12: Taliban seize capital of the southeastern province of Ghazni, forcing officials to retreat to Kabul. Later, group seizes control of Herat and Kandahar provinces.
Aug. 13: Taliban seize control of Lashkar Gah, the capital of Helmand province in the south. On same day, gain control of Badghis, Logar, Uruzgan, Zabul and Ghor provinces with no resistance.
Aug.14: Taliban fighters overrun Mazar-i-Sharif in Balkh province, and then Pul-e-Alam, the provincial capital of Logar province, 70 kilometers (40 miles) south of Kabul.
Aug. 15: Jalalabad, the capital of Nangarhar province, is taken over by the Taliban
Aug. 15: Taliban fighters storm Afghan capital of Kabul, forcing Ashraf Ghani to flee the country.
Aug. 15: US evacuates diplomats from Kabul Embassy.
Aug. 16: In a speech to the nation, US President Joe Biden says, “I do not regret my decision to end America’s warfighting in Afghanistan,” and deflects criticism for the government’s rapid collapse.
Aug. 16: Thousands of civilians gather at Kabul's international airport in an attempt to flee Afghanistan.
Aug. 17: Taliban pledges to protect women's rights "within Islamic law" and establish "inclusive Islamic" government. They also declare "amnesty" and encourage Afghans to return to work.
Aug. 23: Taliban spokesperson Suhail Shaheen warns of "consequences" if foreign forces remain beyond Aug. 31, referring to the date as a "red line."
Aug.t 24: Biden says Washington on pace to finish evacuations by Aug. 31 but keeps door open to extending deadline, citing the need for cooperation from Taliban leadership.
August 24, 2021: The World Bank suspends aid disbursements to Afghanistan, voicing concerns about how the Taliban takeover will affect “the country’s development prospects, especially for women."
August 26, 2021: Taliban spokesman Zabihullah Mujahid says there is “no proof” that al-Qaeda carried out Sept. 11, 2001, attacks from Afghanistan.
August 26, 2021: Several explosions rock Afghanistan's capital Kabul, including two outside the city's airport, killing scores and injuring hundreds. Later in the evening, more explosions were reported, bringing the total number of blasts to six. US CENTCOM commander Gen. Kenneth McKenzie confirms that the bombs killed 12 US soldiers and injured 15 others.
Aug. 26: US evacuates and helps evacuation of around 95,700 people from Afghanistan since Aug. 14.
Aug. 30: US declares the completion of the Afghanistan pullout, ending the 20-year war.