On 7 October 2001, less than a month after the attacks of 11 September, the United States began bombing Afghanistan. By mid-November, the Taliban regime was gone from Kabul. Twenty years later, on 15 August 2021, the Taliban walked back into Kabul as the last American-backed government collapsed, and two weeks later the final American aircraft left Afghan soil. In between lay the longest war in American history: a campaign that began as counterterrorism, became state-building, surged and receded, and ended in a withdrawal that shocked the world with its speed and chaos. This is the story of how a war that began in weeks took twenty years to lose.
The war in images
Origins: 9/11 and the Taliban’s refusal
The Afghanistan War began with the attacks of 11 September 2001. Al-Qaeda, led by Osama bin Laden, had planned the attacks from Afghanistan, where it enjoyed the protection of the Taliban regime. The Taliban, a movement of Pashtun religious students that had emerged from the chaos of the Afghan civil war in the 1990s, had seized Kabul in 1996 and imposed a harsh theocratic rule. It hosted al-Qaeda camps, and bin Laden, a Saudi exile, had become a guest the Taliban leadership, under Mullah Mohammed Omar, would not surrender.
After 9/11, President George W. Bush demanded that the Taliban hand over bin Laden and dismantle al-Qaeda. The Taliban refused, offering instead to try bin Laden before an Islamic court if evidence were provided, a proposal Washington rejected as a stalling tactic. On 7 October 2001, the United States and Britain launched Operation Enduring Freedom, a bombing campaign against Taliban and al-Qaeda targets, supported on the ground by American special forces, CIA officers, and the Northern Alliance, a coalition of Tajik, Uzbek, and Hazara militias that had been fighting the Taliban for years. The United Nations Security Council had already condemned the 9/11 attacks and recognised the right of self-defence, giving the Afghan campaign a breadth of international legal legitimacy that the later Iraq invasion would lack.
The campaign was astonishingly swift. American air power, combined with Northern Alliance ground forces and small teams of special forces calling in precision strikes, shattered Taliban front lines. Kabul fell on 13 November 2001. The Taliban retreated south to Kandahar, then melted into the countryside and across the border into Pakistan. In December 2001, al-Qaeda fighters, including bin Laden, made a stand at Tora Bora, a cave complex in the White Mountains near the Pakistani border. American commanders relied on Afghan militias to seal the escape routes, and bin Laden slipped across the border into Pakistan. His escape would haunt the war for the next decade.
Bonn and the building of a new state
In December 2001, Afghan leaders met in Bonn, Germany, under United Nations auspices, and agreed on an interim administration led by Hamid Karzai, a Pashtun tribal leader with longstanding ties to the anti-Taliban resistance. The Bonn Agreement set out a path to a new constitution, elections, and a rebuilt Afghan state. In January 2002, the International Security Assistance Force (ISAF) deployed to Kabul to provide security, initially limited to the capital. The United States, meanwhile, kept its focus on hunting al-Qaeda remnants rather than on building a state, and its attention was already drifting toward Iraq.
The early years brought genuine progress. A new constitution was adopted in January 2004, establishing an Islamic republic with a strong presidency. Presidential elections in October 2004 confirmed Karzai as president, and parliamentary elections followed in 2005. Millions of Afghan girls returned to school after the Taliban’s ban on female education. Kabul filled with returning refugees, journalists, aid workers, and entrepreneurs. Mobile phones, independent media, and a new generation of educated Afghans transformed urban life. But the new state was shallow. Beyond Kabul, power rested with warlords and strongmen whom the United States had empowered during the invasion. Corruption spread through the government and the security forces. The opium economy, suppressed briefly by the Taliban in 2000–2001, revived and soon made Afghanistan the source of the overwhelming majority of the world’s illicit opium, funding warlords, officials, and insurgents alike.
Crucially, the Taliban were never destroyed. Their leadership regrouped in Quetta, Pakistan, and in the tribal areas along the border, rebuilding networks, recruiting fighters, and waiting. Pakistan’s military and intelligence services, which had helped create the Taliban in the 1990s, maintained ties to the movement even as Pakistan officially allied itself with the United States after 9/11. This double game — American aid flowing to Pakistan while the Taliban found sanctuary on Pakistani soil — would become one of the war’s central, unresolved contradictions.
Insurgency: the Taliban return
By 2005 and 2006, the Taliban insurgency was back in force. Suicide bombings, roadside bombs, and assassinations spread across the south and east, and then across the country. NATO took command of ISAF in 2003 and expanded its presence from Kabul to the provinces, but the coalition was divided: American forces fought a counterterrorism war in the east, while NATO allies, with different rules of engagement and caveats, struggled to hold the south. The Afghan National Army and police, built from scratch with billions of dollars in American training, remained weak, illiterate in large part, riddled with desertion, and dependent on American air power, logistics, and contractors.
The war also became entangled with the drug economy. Helmand province, the heartland of Afghan opium production, became one of the most violent places on earth, as British and then American forces fought the Taliban for control of its poppy fields and smuggling routes. American policy oscillated between eradication, which alienated farmers whose livelihoods depended on poppy, and interdiction, which barely dented the trade. The Taliban taxed the opium trade, earning hundreds of millions of dollars a year, while corrupt officials did the same. The war’s economics favoured endurance over victory for everyone except the civilians caught in between.
By 2008, American commanders were warning that the war was deteriorating. The Taliban controlled large parts of the countryside, the Afghan government’s reach barely extended beyond the cities, and casualties among coalition forces, Afghan forces, and civilians were rising. President Barack Obama, who had campaigned on the argument that Afghanistan was the “good war” neglected in favour of Iraq, faced a choice: escalate or accept stalemate.
The surge, 2009–2011
In December 2009, President Obama announced a surge of 30,000 additional American troops, bringing U.S. forces in Afghanistan to nearly 100,000, alongside tens of thousands of coalition troops. The surge, under General Stanley McChrystal and then General David Petraeus, applied the counterinsurgency doctrine that had been credited with reducing violence in Iraq: clear, hold, and build — drive the Taliban from population centres, hold the ground with Afghan and coalition forces, and build governance and services. American forces flooded into Helmand and Kandahar, the Taliban’s heartland, and violence spiked as they fought for contested districts.
The surge achieved tactical gains. Taliban strongholds in Helmand and Kandahar were cleared, and the insurgency’s momentum was blunted. But the gains were fragile. Afghan governance did not follow the military clearing as intended; local officials remained corrupt or absent, and the Taliban, with sanctuary in Pakistan, could wait out the surge, which Obama had announced would begin drawing down in July 2011. The surge’s timetable, intended to signal to Americans that the commitment was not open-ended, also signalled to the Taliban that endurance would suffice.
On 2 May 2011, the war’s central symbolic objective was achieved. U.S. Navy SEALs, operating from Afghanistan, raided a compound in Abbottabad, Pakistan, and killed Osama bin Laden. The killing of the man who had ordered 9/11 was a moment of catharsis in the United States. But it did not end the war. Al-Qaeda in Afghanistan was already a shadow of its 2001 self, and the Taliban insurgency, which had always been a distinct Afghan movement, fought on. The question that had haunted the war from the start — what, exactly, would count as victory? — remained unanswered.
Drawdown, stalemate, and the Doha agreement
From 2011 onward, the United States drew down. American forces fell from nearly 100,000 in 2011 to under 10,000 by 2016, and the mission shifted from combat to training and advising the Afghan National Defense and Security Forces. The Afghan forces, now more than 300,000 strong on paper, took the lead in fighting, and took the overwhelming majority of casualties. By the late 2010s, Afghan forces were losing thousands of soldiers a year, and the Taliban controlled or contested more territory than at any point since 2001. The Afghan government of President Ashraf Ghani, who succeeded Karzai in 2014 after a disputed election, struggled with corruption, factionalism, and a legitimacy crisis, even as Kabul’s urban society — its media, its universities, its women’s rights movement — continued to flourish under the protection of the foreign presence.
President Donald Trump, elected in 2016 on a promise to end America’s “endless wars,” opened direct negotiations with the Taliban, excluding the Afghan government from the table. The talks culminated on 29 February 2020 in the Doha agreement, signed in Qatar between the United States and the Taliban. Under its terms, the United States committed to withdraw all forces by May 2021, in exchange for Taliban pledges to prevent Afghan soil from being used by terrorists, to engage in intra-Afghan negotiations, and to observe a reduction in violence. The agreement did not require the Taliban to recognise the Afghan government, to disarm, or to accept a ceasefire. Critics, including many Afghan officials, argued that the deal legitimised the Taliban, demoralised the Afghan forces, and set a withdrawal timetable that the Taliban could simply wait out. Supporters argued that it was the only realistic path to ending a war that had become unwinnable at acceptable cost.
President Joe Biden, who inherited the Doha agreement, extended the withdrawal deadline to 11 September 2021, the twentieth anniversary of 9/11, and later moved it forward to 31 August. The decision was framed as ending the war; its implementation would become one of the most chaotic episodes in modern American foreign policy.
The Taliban return and the Kabul evacuation
In the spring and summer of 2021, as American forces withdrew, the Taliban launched a nationwide offensive. District after district fell, often without a fight, as Afghan units, cut off from American air support, logistics, and contractor maintenance, surrendered, fled, or made deals with the Taliban. Provincial capitals fell in rapid succession in August. On 15 August 2021, Taliban fighters entered Kabul. President Ghani fled the country. The Afghan army, which the United States had spent twenty years and tens of billions of dollars building, dissolved in days.
The world watched as thousands of Afghans — former interpreters, officials, journalists, women’s rights activists, and their families — rushed to Hamid Karzai International Airport, desperate to escape. The United States and its allies mounted a massive airlift, evacuating more than 120,000 people in two weeks, one of the largest air evacuations in history. The scenes at the airport became emblematic of the war’s end: Afghans clinging to the landing gear of departing aircraft, falling to their deaths; mothers passing babies over barbed wire to soldiers; long lines of people holding documents that might, or might not, secure a seat. On 26 August 2021, a suicide bombing at Abbey Gate, claimed by the Islamic State’s Afghan branch (ISIS-K), killed 13 American service members and more than 170 Afghan civilians. On 29 August, an American drone strike, intended to kill ISIS-K planners, instead killed ten Afghan civilians, including seven children, in a Kabul home. The final American aircraft left Kabul on 30 August 2021, ending twenty years of war.
The Taliban’s return brought an immediate reversal for Afghan women and girls. Secondary schools for girls were closed, women were barred from most workplaces, universities, and public life, and the Ministry for the Propagation of Virtue and the Prevention of Vice enforced dress codes and restrictions on movement. Afghanistan’s economy collapsed as foreign aid was cut, central bank reserves were frozen, and drought and hunger spread. Millions of Afghans faced food insecurity. The country that the United States had spent two decades trying to build reverted, in many respects, to the conditions from which the war had begun — under the same rulers the war had set out to remove.
Casualties and the cost
The Costs of War Project at Brown University has estimated that more than 243,000 people died directly from war-related violence in the Afghanistan and Pakistan war zones, including Afghan civilians, Afghan security forces, Taliban fighters, and coalition troops, with many more deaths attributable indirectly to the war’s destruction of health, livelihoods, and infrastructure. The United Nations Assistance Mission in Afghanistan (UNAMA), which tracked civilian casualties systematically from 2009, documented tens of thousands of civilian deaths and injuries, with the Taliban and other anti-government elements responsible for the majority. More than 2,400 American service members were killed in Afghanistan, and more than 20,000 were wounded. Coalition partners lost hundreds more, including more than 450 British troops. Afghan security forces bore the heaviest burden, with estimates of more than 60,000 killed. Millions of Afghans were displaced, within Afghanistan and as refugees in Pakistan, Iran, and beyond.
The financial cost to the United States is estimated by the Costs of War Project at more than two trillion dollars for the Afghanistan war, including military operations, reconstruction, veterans’ care, and interest on war borrowing. The Special Inspector General for Afghanistan Reconstruction (SIGAR), the American watchdog created to oversee the reconstruction effort, documented staggering waste, fraud, and failure: schools built that were never used, roads that crumbled, a counter-narcotics effort that left Afghanistan producing more opium than ever, and a reconstruction strategy that, in SIGAR’s words, repeatedly mistook spending for progress.
Key figures
Osama bin Laden (1957–2011): Saudi-born leader of al-Qaeda. Planned the 9/11 attacks from Afghanistan. Killed by U.S. Navy SEALs in Abbottabad, Pakistan, on 2 May 2011.
Mullah Mohammed Omar (c. 1960–2013): Founder and leader of the Taliban. Refused to hand over bin Laden after 9/11. Led the Taliban in exile after 2001; his death, in 2013, was concealed by the movement for two years.
George W. Bush (born 1946): President of the United States, 2001–2009. Ordered the invasion of Afghanistan and set the war’s initial counterterrorism aims, then turned American attention to Iraq.
Hamid Karzai (born 1957): President of Afghanistan, 2001–2014. Led the interim administration after Bonn and won elections in 2004 and 2009. Presided over a government marred by corruption and warlordism.
Ashraf Ghani (born 1949): President of Afghanistan, 2014–2021. A former World Bank official and technocrat who fled Kabul as the Taliban entered the city on 15 August 2021.
Stanley McChrystal (born 1954) and David Petraeus (born 1952): American generals who commanded the surge, applying counterinsurgency doctrine in 2009–2011. McChrystal resigned in 2010 after a magazine profile; Petraeus succeeded him.
Barack Obama (born 1961): President of the United States, 2009–2017. Ordered the 2009 surge and then the drawdown that shifted the war to Afghan forces.
Donald Trump (born 1946): President of the United States, 2017–2021. Opened direct negotiations with the Taliban and signed the Doha agreement in February 2020.
Joe Biden (born 1942): President of the United States, 2021–2025. Carried out the final withdrawal, ending the war in August 2021 amid the chaotic Kabul evacuation.
John Sopko: Special Inspector General for Afghanistan Reconstruction (SIGAR), 2012–2025. His office’s audits and lessons-learned reports documented the reconstruction’s failures in unsparing detail.
Timeline
- 11 September 2001: Al-Qaeda attacks kill nearly 3,000 people in the United States.
- 7 October 2001: Operation Enduring Freedom begins; the United States and Britain bomb Taliban and al-Qaeda targets.
- 13 November 2001: Kabul falls to the Northern Alliance.
- December 2001: Battle of Tora Bora; bin Laden escapes into Pakistan. Bonn Agreement establishes interim administration under Hamid Karzai.
- January 2004: New Afghan constitution adopted.
- October 2004: Hamid Karzai elected president.
- 2005–2006: Taliban insurgency returns in force across the south and east.
- August 2003: NATO takes command of ISAF (expanded nationwide in following years).
- December 2009: President Obama announces the surge of 30,000 troops.
- 2 May 2011: Osama bin Laden killed in Abbottabad, Pakistan.
- 2011–2014: Drawdown; Afghan forces take the lead; NATO combat mission ends December 2014.
- September 2014: Ashraf Ghani becomes president after disputed election.
- 29 February 2020: Doha agreement signed between the United States and the Taliban.
- April 2021: President Biden announces full withdrawal by 11 September 2021.
- August 2021: Taliban offensive captures provincial capitals in rapid succession.
- 15 August 2021: Taliban enter Kabul; President Ghani flees.
- 26 August 2021: ISIS-K suicide bombing at Abbey Gate kills 13 U.S. service members and more than 170 Afghans.
- 30 August 2021: Last U.S. aircraft leaves Kabul; the war ends.
The legacy
The Afghanistan War began as a war of necessity, with broad international support, against the regime that had sheltered the authors of 9/11. It ended as a war of exhaustion, with the same regime back in power, the country’s women stripped of rights won over twenty years, and America’s credibility damaged by the chaos of the exit. The war’s defenders argue that it prevented another 9/11 from Afghan soil for twenty years, that it gave a generation of Afghans — especially girls — an education and a glimpse of a different life, and that its failure lay in the withdrawal, not in the war itself. Its critics argue that the war was lost long before 2021, in the decision to attempt state-building in a country whose institutions could not sustain it, in the tolerance of Pakistani sanctuary and Afghan corruption, and in the refusal, across four administrations, to reckon honestly with what the war could and could not achieve.
The deeper lesson, recorded in SIGAR’s lessons-learned reports and in the Costs of War accounting, is about the limits of power: that a superpower can topple a regime in weeks, can spend two trillion dollars, can train an army of hundreds of thousands — and still cannot build a state that survives its departure. The Afghan people, who bore the war’s heaviest cost, live with the result. The war is over for America. For Afghanistan, its consequences are still unfolding.
Sources and further reading
- National Commission on Terrorist Attacks Upon the United States, The 9/11 Commission Report, 2004.
- Agreement on Provisional Arrangements in Afghanistan Pending the Re-establishment of Permanent Government Institutions (Bonn Agreement), December 2001, United Nations.
- Agreement for Bringing Peace to Afghanistan (Doha Agreement), 29 February 2020, U.S. Department of State.
- Special Inspector General for Afghanistan Reconstruction (SIGAR), Lessons Learned reports and quarterly reports to Congress.
- Costs of War Project, Brown University, estimates of deaths and U.S. costs of the Afghanistan War.
- United Nations Assistance Mission in Afghanistan (UNAMA), Protection of Civilians in Armed Conflict reports.
- Steve Coll, Ghost Wars: The Secret History of the CIA, Afghanistan, and Bin Laden (2004) and Directorate S: The CIA and America’s Secret Wars in Afghanistan and Pakistan (2018).
- Craig Whitlock, The Afghanistan Papers: A Secret History of the War (2021).
- Carter Malkasian, The American War in Afghanistan: A History (2021).
- Encyclopaedia Britannica, “Afghanistan War” entry, and U.S. Department of Defense casualty releases.