Costs

U.S. Federal Budget

The economic costs of military interventions take many forms, including the increased costs to the federal budget – including not only the costs borne by the Department of Defense, but also increased costs for veterans’ benefits. In the case of the “post-9/11 wars,” including and beyond the U.S.-led wars in Afghanistan and Iraq, war costs also include spending on Department of Homeland Security efforts within the U.S. to prevent and counter terrorism. Future spending is obligated for veterans’ care, and there are increased interest payments on war borrowing. For this reason, even after the withdrawal of U.S. troops from Afghanistan in 2021, budgetary costs continue to increase.

U.S. post-9/11 war costs also includes local and state public spending – untallied by Costs of War -- and spending on U.S. foreign assistance for reconstruction in post-9/11 war zones.

The post-9/11 wars were funded largely through debt, rather than through increased taxes or the sale of war bonds, as U.S. wars of the past were funded. The use of debt rather than increased taxes makes war more invisible to taxpayers, obscuring the true costs of war by pushing financial obligations to future generations. Moreover, increased public debt results in higher interest rates economy-wide, which can hamper business investments and make life more expensive for individuals and families.

Since the U.S. withdrawal from Afghanistan in 2021, the Pentagon as well as advocates for increased U.S. military spending focus on China and Russia as the new national security challenge, terming this “great power competition.” U.S. discourses about security threats from China and Russia are characterized by threat inflation. The U.S. outspends all other countries in the world on military expenditures.

Key Findings

U.S. Federal Spending

In the one year following October 2023, the U.S. spent $17.9 billion to support Israel’s military operations in Gaza and elsewhere, and an additional $4.86 billion on related U.S. operations in the region, including in Yemen.
The U.S. spends 2-3 times as much as China in military spending, even after accounting for differences in labor costs and purchasing power.
While the Russian military maintains the world’s largest stockpile of nuclear weaponry, the Russian defense budget amounts to less than 1/10 of the U.S. defense budget. Western strategists have a long tradition of overinflating Russia as a military threat.

Spending on the Post-9/11 Wars

Between the start of the post-9/11 wars in late 2001 through fiscal year 2022, the U.S. appropriated and is obligated to spend an estimated $8 trillion for the post-9/11 wars — an estimated $5.8 trillion in appropriations, plus an additional minimum of $2.2 trillion for obligations to care for the veterans of these wars through the next several decades.
Of the $8 trillion total, about $2.3 trillion were spent on the budget category for post-9/11 military operations, “Overseas Contingency Operations.” Over $1 trillion has already been spent on interest payments, since these operations have been funded entirely through debt. The base budget of the Pentagon has increased by about $900 billion above what it would have been in the absence of war; Homeland Security spending on preventing and countering terrorism within the U.S. has totaled over $1.1 trillion since the inception of the Department of Homeland Security in 2002; and current and future costs for veterans has added nearly $2.2 trillion and that figure will continue to grow.
From 2001 to 2019, the U.S. spent over $2 trillion on the war in Afghanistan.
In the 20 years of war from 2003 to 2023, the U.S. spent and obligated over $2.89 trillion on the wars in Iraq and Syria ($1.79 trillion spent through 2023, plus $1.1 trillion in obligations for future veterans’ care).
These federal expenditures and obligations do not include many other types of budgetary costs, including state and local government spending, private costs, future interest payments, or opportunity costs. Nor do they include costs to foreign governments or economies.
Western allies of the United States bore significant costs in the post-9/11 wars, in terms of both dollars and lives. When measured as a percentage of their annual baseline military expenditures, the United Kingdom and Canada spent roughly half as much on Afghanistan as the United States. And when measured in terms relative to their respective Gross Domestic Products (GDPs), the U.S. provided less foreign aid than did the U.K., and about the same amount as Germany and Canada.

Future U.S. Spending

As veterans continue to bear huge physical and mental costs from the post-9/11 wars, the costs of caring for these veterans will reach between $2.2 and $2.5 trillion by 2050 – most of which has not yet been paid. The U.S. risks shortchanging its promises to these veterans if the government does not make adequate budgetary commitments.

The costs associated with caring for veterans do not reach their peak until decades after the wars they fought, as veterans’ needs increase with age. Expenditures to care for veterans doubled from 2.4 percent of the total federal budget in FY 2001 to 4.9 percent in FY 2020, even as the total number of living veterans from all U.S. wars declined from 25.3 million to 18.5 million.

The post 9/11 wars were “credit card wars.” By 2030, the U.S. will have spent as much on interest payments as it did on “overseas contingency operations” for the wars themselves – over $2 trillion.

Homeland Security

The creation of the new cabinet-level Homeland Security agency after 9/11 and the associated identification of a new homeland security mission to prevent, respond to, and recover from terrorist attacks, constituted the largest reorganization in the U.S. government since World War II. Activities considered “homeland security” are carried out by the federal government as well as by state and local governments, especially law enforcement officers, and private entities. Federal government expenditures fall under Customs and Border Patrol, Immigration and Customs Enforcement, the Transportation Security Administration, and others.
Since the creation of the Department of Homeland Security in 2003, outlays for DHS have totaled over $1.1 trillion as of 2025, according to the Office of Management and Budget .
State and municipal governments also spend a significant amount on homeland security, but the total is difficult to calculate given a lack of government data.

Reconstruction

The costs of war include U.S. funding for international assistance, including reconstruction activities where military interventions have destroyed various types of infrastructure. Reconstruction work has traditionally been undertaken by the Department of State or the U.S. Agency for International Development (USAID), though it is increasingly now being undertaken by the military. Regardless of the agency or department receiving the funds, spending on “reconstruction” and international aid has increasingly gone to security purposes in recent years, including to local police and military.

(Page updated as of June 2025)