The War in Afghanistan was an armed conflict from 2001 to 2021. It was the direct response to the September 11 attacks. It began when an international military coalition led by the United States launched an invasion of Afghanistan, declaring Operation Enduring Freedom as part of the earlier-declared war on terror; toppling the Taliban-ruled Islamic Emirate and establishing the Islamic Republic three years later. The Taliban and its allies were expelled from major population centers by the US-led forces, supporting the anti-Taliban Northern Alliance; however Bin Laden relocated to neighboring Pakistan. The conflict officially ended with the 2021 Taliban offensive, which overthrew the Islamic Republic, and re-established the Islamic Emirate. It was the longest war in the military history of the United States, surpassing the length of the Vietnam War (1955–1975) by approximately six months.

The Northern Alliance, officially known as the United Islamic National Front for the Salvation of Afghanistan, was a military alliance of groups that operated between early 1992 and 2001 following the dissolution of the Soviet Union. At that time, many non-Pashtun Northerners originally with the Republic of Afghanistan led by Mohammad Najibullah became disaffected with Pashtun Khalqist Afghan Army officers holding control over non-Pashtun militias in the North. Defectors such as Rashid Dostum and Abdul Momim allied with Ahmad Shah Massoud and Ali Mazari forming the Northern Alliance. The alliance's capture of Mazar-i-Sharif and more importantly the supplies kept there crippled the Afghan military and began the end of Najibullah's government. Following the collapse of Najibullah's government the Alliance would fall with a Second Civil War breaking out however following the Islamic Emirate of Afghanistan's (Taliban) takeover of Kabul, The United Front was reassembled.