CRS – Afghanistan: Background and U.S. Policy:In Brief Updated March 25, 2021: “Afghanistan emerged as a significant U.S. foreign policy concern in 2001, when the United States, in response to the terrorist attacks of September 11, 2001, led a military campaign against Al Qaeda and the Afghan Taliban government that harbored and supported it. In the intervening 19 years, the United States has suffered over 22,000 military casualties (including around 2,400 fatalities) in Afghanistan and Congress has appropriated approximately $143 billion for reconstruction and security forces there. In that time, an elected Afghan government has replaced the Taliban; improvement in most measures of human development is limited; and future prospects of gains remain mixed. In January 2021, the Trump Administration reported that it had reduced U.S. forces in Afghanistan to 2,500, the lowest level since 2001, in advance of the potential full military withdrawal by May2021 to which the United States committed in the February 2020 U.S.-Taliban agreement.As part of that agreement, in return for the full withdrawal of international forces, the Taliban committed to preventing other groups, including Al Qaeda, from using Afghan soil to recruit, train, or fund raise toward activities that threaten the United States or its allies. The agreement is accompanied by text which, according to Chairman of the Joint Chiefs of Staff General Mark Milley, contains additional Taliban commitments, including to not attack U.S. or international forces. U.S. officials contend that the Taliban have not fulfilled their commitments, and describe the prospective U.S. withdrawal as “conditions-based,” but have not specified exactly what conditions might halt, reverse, or otherwise alter the withdrawal timeline laid out in the agreement…”