A groundbreaking report by Brown University’s Watson Institute for International and Public Affairs has laid bare the immense human and financial toll of the United States’ global military operations since 2001, revealing that these wars have cost $5.8 trillion and led to the deaths of up to 4.7 million people. Published under the title “Costs of War”, the report documents the direct and indirect consequences of U.S. interventions in countries including Afghanistan, Iraq, Syria, Yemen, and others. It details how the U.S., under the pretext of fighting terrorism or searching for weapons of mass destruction, waged large-scale wars that devastated entire regions and caused extraordinary civilian suffering.
The research states that approximately 940,000 people were directly killed in combat, including over 30,000 American soldiers, contractors, and allied forces. However, when accounting for indirect deaths caused by the collapse of healthcare systems, food insecurity, displacement, and disease, the estimated death toll rises dramatically to between 4.5 and 4.7 million.
Iraq witnessed the worst human cost of these wars, where around 315,000 people lost their lives of which an estimated 215,000 were civilians making it the single deadliest theatre of war in terms of civilian casualties among all U.S.-led interventions.
In Afghanistan, where American forces were engaged for two decades, the death toll reached 243,000, including 70,000 civilians. The long-running conflict also destabilized neighboring Pakistan, leading to the deaths of thousands more and triggering lasting security, political, and humanitarian challenges for the region.
Together, the wars in Iraq and Afghanistan accounted for more than 558,000 direct fatalities. The U.S. military also intervened in Syria’s civil war in 2014. By 2021, the conflict had claimed approximately 269,000 lives, including 139,000 civilians. In Yemen, where American involvement included logistical and intelligence support to the Saudi-led coalition, the war has caused at least 112,000 deaths.
The Costs of War report paints a damning picture of the long-term consequences of American military adventurism. While these operations were justified under shifting narratives—initially launched in the name of national security and later reframed as humanitarian or stabilization efforts the real cost was borne by ordinary people across the Middle East and South Asia.
Experts argue that the vast financial resources expended on war estimated at $5.8 trillion could have been redirected to global health, education, and climate initiatives. Instead, the militarization of U.S. foreign policy has left behind a legacy of broken nations, displaced populations, and deepening anti-American sentiment.
The findings from Brown University serve as a stark reminder of the profound human and strategic consequences of two decades of unending conflict—raising pressing questions about the accountability, morality, and sustainability of global military interventions in the post-9/11 era.
