War in Afghanistan (2001-2021): From 9/11 to the Fall of Kabul

The War in Afghanistan was the armed conflict that began with the US-led invasion of Afghanistan on 7 October 2001, launched in response to the September 11 attacks, and ended with the withdrawal of the last American troops on 30 August 2021. The Taliban regime was overthrown within weeks, but the movement regrouped and fought a long insurgency against the new Afghan state and its NATO allies. Lasting almost 20 years, it was the longest war in American history, and it ended with the Taliban back in power.

Background

Afghanistan had been at war almost continuously since the Soviet invasion of 1979. After the Soviet withdrawal in 1989 and the fall of the communist government in 1992, rival mujahideen factions fought a destructive civil war. Out of this chaos rose the Taliban (“students”), a movement of religious students and former fighters from the Pashtun south led by Mullah Mohammad Omar. They took Kabul in 1996 and imposed a strict interpretation of Islamic law, banning girls from school and women from most work.

The Taliban gave refuge to Osama bin Laden, whose al-Qaeda network ran training camps in the country. After al-Qaeda carried out the September 11 attacks, the United States demanded that the Taliban hand over bin Laden and close the camps. Mullah Omar refused.

Invasion and the fall of the Taliban (2001)

Operation Enduring Freedom began on 7 October 2001 with American and British air strikes. On the ground, the campaign relied on the Northern Alliance, a coalition of mainly Tajik, Uzbek and Hazara forces that had resisted the Taliban for years, supported by small teams of CIA officers and US special forces who directed precision air strikes.

The Taliban collapsed faster than almost anyone expected. Mazar-i-Sharif fell on 9 November, Kabul was abandoned on 13 November, and Kandahar, the Taliban’s spiritual heartland, surrendered in early December. In December 2001 US-backed Afghan militias attacked al-Qaeda fighters in the cave complexes of Tora Bora, but bin Laden escaped, almost certainly into Pakistan.

At a UN-sponsored conference in Bonn, Afghan factions agreed on 5 December 2001 to an interim government headed by Hamid Karzai, a Pashtun leader from Kandahar. On 20 December the UN Security Council authorised the International Security Assistance Force (ISAF) to help secure Kabul.

Building a new state (2002-2005)

For several years the country was relatively calm. A loya jirga (grand assembly) confirmed Karzai as interim president in 2002, a new constitution was adopted in January 2004, and in October 2004 Karzai won Afghanistan’s first direct presidential election. Millions of refugees returned, girls went back to school, and new roads, clinics and a national army were built with international money.

The foundations were weak, however. The United States shifted its attention and resources to the Iraq War from 2003. The Afghan government depended heavily on foreign aid and on regional strongmen and former warlords, and corruption grew. Opium production expanded, and Afghanistan became the source of most of the world’s illicit opium. Meanwhile Taliban leaders reorganised in Pakistan, where the city of Quetta became their base.

The insurgency and NATO’s war (2006-2014)

NATO took command of ISAF in August 2003, its first major operation outside Europe, and between 2004 and 2006 extended it across the whole country. British, Canadian, Dutch and other troops moved into the southern provinces of Helmand, Kandahar and Uruzgan in 2006, just as the Taliban launched a major offensive. What many governments had presented as a peacekeeping and reconstruction mission became heavy fighting.

The insurgency used ambushes, suicide bombings and above all roadside bombs, known as improvised explosive devices, which caused most coalition casualties. Civilian deaths from both insurgent attacks and coalition air strikes eroded support for the government and its allies. Karzai’s disputed re-election in 2009, marked by widespread fraud, deepened doubts about the Afghan state.

In December 2009 President Barack Obama announced a “surge” of 30,000 extra American troops, while also setting a date to begin withdrawing them. US troop numbers peaked at about 100,000 in 2010-2011, and total ISAF strength at around 130,000. The surge pushed the Taliban out of parts of Helmand and Kandahar, but did not break the movement. On 2 May 2011 US special forces killed bin Laden in Abbottabad, Pakistan (see the killing of Osama bin Laden), removing one of the original reasons for the war.

Responsibility for security was handed to Afghan forces in stages. ISAF ended on 28 December 2014 and was replaced from January 2015 by a smaller NATO training mission, Resolute Support. The Afghan army and police now did most of the fighting and dying.

Key people

Hamid Karzai led Afghanistan from December 2001 until 2014; his relationship with Washington became increasingly strained. Ashraf Ghani, a former World Bank official, succeeded him in 2014 after another disputed election. Mullah Mohammad Omar, the reclusive Taliban leader, died in 2013, though his death was concealed until 2015. Hibatullah Akhundzada became Taliban leader in 2016, and Abdul Ghani Baradar led its negotiating team in Qatar.

Four American presidents oversaw the war: George W. Bush, who launched it; Barack Obama, who ordered the surge and killed bin Laden; Donald Trump, whose administration negotiated with the Taliban; and Joe Biden, who carried out the final withdrawal.

Withdrawal and the fall of Kabul (2020-2021)

On 29 February 2020 the United States and the Taliban signed the Doha Agreement in Qatar. Washington promised to withdraw all its forces within 14 months; the Taliban pledged not to let al-Qaeda or other groups use Afghanistan to threaten the United States and to negotiate with the Afghan government, which was not a party to the deal. Talks between the Afghans began in September 2020 but made little progress.

In April 2021 President Biden announced that all US troops would leave by 11 September 2021, and other NATO countries followed. The Taliban launched a nationwide offensive in May. Many Afghan units, unpaid, poorly supplied and demoralised, surrendered or melted away. Provincial capitals fell one after another in early August, and on 15 August 2021 Taliban fighters entered Kabul as President Ghani fled the country.

A chaotic airlift followed from Hamid Karzai International Airport, where crowds of Afghans desperate to leave besieged the gates. On 26 August a suicide bomber from the Islamic State’s local branch (ISIS-K) killed 13 US service members and an estimated 170 or more Afghans at the airport’s Abbey Gate. In all, more than 120,000 people were evacuated. The last US military aircraft left shortly before midnight on 30 August 2021.

By the numbers

Casualty figures for Afghan civilians and fighters are estimates, mainly from Brown University’s Costs of War project, and the true totals may be higher. Estimates of the total American financial cost range up to more than 2 trillion dollars.

Consequences and legacy

The Taliban restored the Islamic Emirate of Afghanistan. Despite early promises of moderation, they barred girls from secondary school in March 2022 and women from universities in December 2022, and imposed wide restrictions on women’s work and movement. No country formally recognised the new government in its first years, foreign aid was largely cut off, and the economy contracted sharply, deepening a humanitarian crisis.

The war’s balance sheet remains debated. Al-Qaeda lost its safe haven in 2001 and was greatly weakened, and for two decades Afghans, especially in the cities, gained wider access to education, health care and media. Yet the effort to build a stable, self-sufficient Afghan state failed. Government documents published in 2019 as “The Afghanistan Papers” showed that many officials had privately doubted progress for years. For the United States and its allies, the fall of Kabul became a symbol of the limits of military intervention and nation-building.

Timeline

• 2001, 7 October: US and British air strikes begin Operation Enduring Freedom.
• 2001, 13 November: Taliban forces abandon Kabul to the Northern Alliance.
• 2001, 5 December: The Bonn Agreement names Hamid Karzai head of an interim administration.
• 2003, 11 August: NATO takes command of ISAF.
• 2009, 1 December: President Obama announces a surge of 30,000 US troops.
• 2011, 2 May: Osama bin Laden is killed in Abbottabad, Pakistan.
• 2014, 28 December: ISAF’s combat mission formally ends.
• 2020, 29 February: The United States and the Taliban sign the Doha Agreement.
• 2021, 15 August: The Taliban enter Kabul as President Ghani flees.
• 2021, 30 August: The last US forces leave Afghanistan.

Why it matters

The War in Afghanistan was the first and longest campaign of the “War on Terror” and NATO’s largest operation outside Europe. Its ending, with the return of the very movement it had overthrown, has shaped debates in Western countries about when and how to intervene abroad, and left millions of Afghans living under Taliban rule once more.