From the Summary: "Afghanistan was elevated 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 Taliban government that harbored and supported it. In the intervening 18 years, the United States has suffered around 2,400 military fatalities in Afghanistan (including four in combat in 2020 to date) and Congress has appropriated approximately $137 billion for reconstruction there.In that time, an elected Afghan government has replaced the Taliban, and most measures of human development have improved, although future prospects of those measures remain mixed. The fundamental objective of U.S. efforts in Afghanistan is 'preventing any further attacks on the United States by terrorists enjoying safe haven or support in Afghanistan,' according to the State Department's Integrated Country Strategy."
CRS Report for Congress, R45122
Congressional Research Service: https://crsreports.congress.gov/