25 Years After 9/11: Assessing U.S. Military Impact

On September 11, 2001, 2,977 people were killed in terrorist attacks in the United States, marking a significant event in global history. In response, the U.S. invaded Afghanistan in October 2001 and Iraq in 2003, leading to what became known as the Global War on Terror.

According to Brown University’s Costs of War project, these conflicts resulted in at least 940,000 direct deaths and an estimated 3.6–3.8 million indirect deaths due to war-related consequences. Additionally, over 38 million people were displaced, and the financial cost to the U.S. reached approximately $8 trillion by 2021.

The article notes that while military force can disrupt terrorist networks, it cannot alone provide the political legitimacy and social cohesion necessary for lasting security. The U.S. military completed its withdrawal from Afghanistan in August 2021 and ended its combat role in Iraq in December 2021, transitioning to an advisory role.