The U.S. war in Afghanistan has been the longest in American history, lasting 20 years. In the conflict’s second decade, plans for an exit of U.S. forces were repeatedly put off, but President Joe Biden finally withdrew most of them by August 2021 and NATO-led allied troops followed suit. The drawdown of foreign forces was met by unexpectedly swift battlefield advances by the Taliban, Islamic fundamentalists who ruled the country before the U.S. invasion. In mid-August, after retaking most of the country, they entered the capital Kabul, prompting the return of some foreign troops to help evacuate diplomats. The roots of the conflict stretch back at least 40 years.
In 1979, the Soviet Union invaded Afghanistan and installed a Marxist puppet regime, an attempt to impose order after two separate coups. Millions of Afghanis fled to Pakistan and other nearby countries, while thousands of others took up arms against the Red Army. The U.S., seeing a chance to stymie its Cold War foe, provided weapons to Afghan militias, including radical Islamist factions. In 1989, the Soviet military pulled out.