America’s Longest War

When U.S. troops leave Afghanistan by September 11, 2021, the American war will have lasted nearly two decades and spanned four presidencies. The longest war in U.S. history has come at the financial cost of close to $1 trillion. It has killed more than 2,000 American soldiers and, according to some estimates, hundreds of thousands of Afghans.

The United States invaded Afghanistan on October 7, 2001. President George W. Bush authorized the war in response to 9/11—Taliban-ruled Afghanistan was providing refuge for al Qaeda, the terrorist organization that had orchestrated the attacks. Al Qaeda’s leader, Osama bin Laden, evaded the U.S. military for a decade, but the Taliban regime fell within weeks. U.S. and allied forces stayed in Afghanistan to support a new government in Kabul. But the Taliban soon regrouped. For years, the fighting ebbed and surged as Washington tossed around versions of the same questions: With more time and resources, could the U.S. military finally rout the Taliban and the terrorists they had harbored? Was staying the course a better option than risking the collapse of the fledgling Afghan state? Or was it necessary to find a way out, whether by negotiation or unilateral withdrawal?

Over the past two decades, senior officials—including U.S. ambassadors, commanders of U.S. and NATO military forces, and the current president of Afghanistan—as well as leading scholars and journalists have assessed the progress of the war and the prospects of its resolution in the pages of Foreign Affairs. Their essays in this collection trace the conflict from the initial invasion to the 2009 surge, the bloody stalemate, and the decision to withdraw. And, as the war enters its final months, they consider its consequences for Afghanistan and its lessons for the United States.