On 15 August 2021, Afghanistan's capital city of Kabul was captured by the Taliban after a major insurgent offensive that began in May 2021. It was the final action of the War in Afghanistan, and marked a total victory for the Taliban. This led to the overthrowing of the Islamic Republic of Afghanistan under President Ashraf Ghani and the reinstatement of the Islamic Emirate of Afghanistan under the control of the Taliban.
The US–Taliban deal, signed on 29 February 2020, is considered one of the most critical factors that caused the collapse of the Afghan National Security Forces (ANSF). Following the deal, the US dramatically reduced the number of air attacks and deprived the ANSF of a critical edge in fighting the Taliban insurgency.
Months before the fall, many in the United States Intelligence Community estimated that Kabul would be taken at least six months after the withdrawal of US troops from Afghanistan was completed. However, beginning in May 2021, even while the withdrawal was occurring, the Taliban was able to take most of Afghanistan's provinces in rapid succession during a major offensive. During this period, estimates for the longevity of the Afghan state declined significantly. Ultimately, US President Joe Biden conceded on 16 August that the collapse "unfold[ed] more quickly than [they] had anticipated".
Between 14 August and 31 August 2021, the US and its coalition partners evacuated more than 123,000 people from Afghanistan via airlifts from Kabul International Airport (known then as Hamid Karzai International Airport). During the evacuation, the airport remained under NATO and US military control despite the collapse of the central government. Evacuees included foreign diplomatic staff and military personnel, third-country civilians, Afghan allies and vulnerable Afghans such as journalists and human rights activists. The airlift was the largest non-combatant evacuation operation in US military history, with US military personnel transferring 79,000 civilians through the airport and out of Afghanistan over the 18-day mission.
After the United States' withdrawal on 31 August, a group of about 1,000 people, including US citizens and Afghans holding American visas, were still stranded in Kabul. Two weeks later, secretary of state Antony Blinken said it was several thousand US residents and one hundred US citizens.
Background
US–Taliban deal
The US–Taliban deal, also known as the "Agreement for Bringing Peace to Afghanistan", was a peace agreement signed by the United States and the Taliban on 29 February 2020 in Doha, Qatar. The deal was meant to bring the war in Afghanistan to an end. Significantly, the deal did not involve the then Afghan government.
The deal stipulated fighting restrictions for both the US and the Taliban, including the withdrawal of all NATO forces from Afghanistan in return for counter-terrorism commitments from the Taliban. The US agreed to an initial reduction of its force level from 13,000 to 8,600 within 135 days (i.e., by July 2020), followed by a full withdrawal within 14 months (i.e., by 1 May 2021) if the Taliban kept its commitments. The US also committed to closing five military bases within 135 days, and expressed its intent to end economic sanctions on the Taliban by 27 August 2020.
The deal had a significant impact on the Afghan National Security Forces. US support for the Afghan military was significantly reduced. And according to the terms of the deal, US military aircraft could not attack Taliban groups waiting more than 500 meters away, giving the Taliban an edge in targeting Afghan military units.
The deal also exacerbated the decline in morale of the Afghan army and police, leading to members bargaining with the Taliban. The Taliban was also able to spread propaganda and disinformation about the agreement, due to a lack of information and secret annexes in the agreement that were unknown even to the then Afghan government. The Taliban propaganda aimed to convince local police and military units that the US had already handed over territories to the Taliban, and that they should abandon their positions too.
2021 Taliban offensive
Weeks before the offensive, in April 2021, the US State Department urged American civilians in Afghanistan to "leave as soon as possible on available commercial flights".
On 1 May 2021, the Taliban and allied militant groups began a widespread offensive shortly after a significant portion of US troops withdrew from Afghanistan.