War in Afghanistan (2001–2021)
The War in Afghanistan was a conflict that took place from 2001 to 2021 in Afghanistan. It started with an invasion that led to the United States and its allies toppling the Taliban-ruled Islamic Emirate of Afghanistan in order to deny al-Qaeda a safe base of operations in the country. For most of the period, the war was officially fought between allied NATO and Afghan Armed Forces, and opposing Taliban insurgents. The Taliban regained power 19 years and 8 months later after defeating the Afghan Armed Forces following the withdrawal of most NATO forces. It was the longest war in United States history, surpassing the Vietnam War by roughly five months.