Finally, the world has seen the withdrawal of American forces from Afghanistan after a long period of time. The US army stayed in Afghanistan for almost 20 years after the 9/11 attacks. The withdrawal of US forces from Afghanistan has taken place in wake of the Doha Agreement which was signed by the Trump administration and Taliban in 2020.
In this agreement, the Taliban assured the Trump administration that all efforts will be taken to stop al-Qaeda from operating in Taliban-controlled areas as well as there will be negotiations between the Taliban and the future Afghan government in pursuit of a permanent ceasefire.
Trump administration agreed for gradual reduction of forces of United States from 13000 to 8600 by the end of July 2020, to be followed by complete withdrawal latest by 1st May 2021. The withdrawal was conditioned with compliance from the Taliban for what they agreed.
The Taliban began a final offensive on 1 May. On 8 July, Biden specified a new completion date of 31 August. Biden considered but rejected extending the withdrawal deadline beyond 31 August. There were about 650 US troops in Afghanistan in early August 2021, tasked with protecting the airport and embassy. US intelligence assessments estimated as late as July that Kabul would fall within months or weeks following the withdrawal of all American forces from Afghanistan, though the security situation deteriorated rapidly.
Summarising we can say that Doha Agreement served as a critical point in the withdrawal of US forces from Afghanistan since after this agreement American Government, after achieving all objectives, decided no to say any further in Afghanistan.