The Costs of War to U.S. Allies since 9/11


Jason W. Davidson | Watson Institute/Brown University – TRANSCEND Media Service

12 May 2021

The United States’ allies in the post-9/11 wars have borne significant human and budgetary costs, and these costs should be included in a full accounting of the consequences of these wars. The ‘post-9/11 wars’ refers to U.S.-led military operations in Afghanistan and Iraq that have grown out of President George W. Bush’s “Global War on Terror” and the U.S. invasion of Afghanistan in 2001. While Afghan and Iraqi government security forces have incurred the highest human costs of these wars, this research paper focuses on the human and financial contributions of European and other allies of the U.S.

Assessing the costs to allies informs current scholarly and policy debates on the value of U.S. military alliances. President Donald Trump, for example, failed to acknowledge the value of most U.S. alliances; for instance, he threatened to leave South Korea and Japan to defend themselves and talked repeatedly about withdrawing the U.S. from NATO.  In contrast, President Joe Biden’s administration stresses the myriad benefits allies bring to the U.S. as a reason to rekindle the relationships that suffered during the Trump presidency.

This paper documents what U.S. allies have spent, in human lives and in resources, on their participation in U.S.-led military operations since September 11, 2001. It examines the top five suppliers of troops to military operations in Afghanistan and Iraq during the year of peak coalition deployment for each conflict (2011 and 2006 respectively). It examines the size of U.S. and allied deployments relative to each country’s populations at the time. Then, turning to the longer war period from 2001 to 2018, the paper tallies each allied nation’s total fatalities and considers these numbers relative to the size of their deployments. The paper also compares U.S. and each ally’s military spending for the wars. Finally, it outlines U.S. and allied spending on foreign aid to Afghanistan and Iraq through 2018.

In general, allies incurred these costs primarily to further their alliances with the United States. The discussions in each of the following sections on Afghanistan and on Iraq draw on existing scholarship to suggest why each ally contributed to the extent it did. These are not definitive explanations (which would require extensive interviews with allied decision makers), but are intended to suggest potential avenues for future research.


Allied countries’ provision of troops to the US-led military intervention in Afghanistan dates to the earliest days of Operation Enduring Freedom in 2001, when the coalition’s goal was to kill and capture Al Qaeda members and overthrow the Taliban regime that had hosted Al Qaeda leading up to the September 11, 2001 attacks on the Twin Towers and Pentagon. After those initial moments of the war, allied contributions continued under the North Atlantic Treaty Organization (NATO)’s International Security Assistance Force (ISAF). At the coalition’s peak size (in terms of troop totals) in February 2011, the U.S. deployed roughly 100,000 troops and all other allies’ deployments totaled 41,893 troops.

Table 1 lists the top five non-U.S. suppliers of troops to ISAF in February 2011: the United Kingdom, Germany, France, Italy, and Canada. At that time—almost ten years after the first coalition forces arrived in Afghanistan—forty-seven countries had troops deployed to Afghanistan. While none of the top troop providers approached the U.S. deployment, either in size or as a percentage of their populations, they all made substantial contributions. The United Kingdom stands out in that it supplied roughly two to three times the troops of the other top contributing allies when considered relative to its population. Each of the other top providers made a similar contribution on a per capita basis, deploying roughly 0.006% of their populations.

Table 1: Top Troop Suppliers to Afghanistan as of February 2011

Country Troops as % of Population

United States 100,000 .032

United Kingdom 9,500 .015

Germany 4,920 .006

France 4,000 .006

Italy 3,770 .006

Canada 2,905 .008

Table 2 compares the top suppliers in terms of the number of fatalities they incurred from the start of the war in 2001 through 2018: the UK, Canada, France, Germany, and Italy. While the U.S. had the largest total number of fatalities, the allies were not mere bystanders, as some believe. Some U.S. military service members, for instance, joked that ISAF stood for “I Saw Americans Fight” because of all the caveats and limits on when and how some allies could engage the enemy. Yet hundreds of allied troops died. The United Kingdom lost 455 service members, Canada lost 158, and France, Germany, and Italy each lost dozens.

When we look at numbers of fatalities relative to the size of each country’s deployment, Canadian soldiers suffered the highest risk of dying, with their 158 fatalities accounting for 5.4% of Canada’s peak deployment in 2011. The United Kingdom’s 455 fatalities amounted to 4.7% of its peak deployment in 2011. In comparison, the U.S. incurred 2,316 fatalities, which was 2.3% of its peak deployment in 2011. These numbers demonstrate that British and Canadian troops were not hiding from the fight—they put their lives at risk at twice the rate of American troops, when seen as a percentage of peak deployment. France’s fatalities as a percentage of peak deployment were similar to those of the U.S., and Germany and Italy were close behind.

Table 2: Top Allied Fatalities in Afghanistan, October 2001-September 2017

Country Fatalities as % of Peak Deployment

United States 2,316 2.3

United Kingdom 455 4.7

Canada 158 5.4

France 86 2.1

Germany 54 1.0

Italy 48 1.2

Allied nations also spent significant sums of money on their military presence in Afghanistan (Table 3). While at first glance the level of allied spending might seem insignificant relative to U.S. spending, it is useful to consider each ally’s spending in Afghanistan as a percentage of that ally’s total annual defense spending. This comparison puts each country’s spending in Afghanistan in relation to its total military budget, and enables a comparison of allied and U.S. spending in relative terms.

When we consider each country’s spending as a percentage of its total military expenditure in one year, the United Kingdom’s 2001-18 military spending on Afghanistan was roughly half the U.S. figure. Whereas the U.S. spent over one hundred percent of its baseline on seventeen years of its campaign in Afghanistan, the UK spent 56% of its baseline spending in Afghanistan over the same time period. Canada’s military spending on Afghanistan was also roughly half of U.S. spending as a percentage of its baseline. Italy spent a third of its baseline spending on its Afghanistan operations whereas Germany spent a quarter of its expenditures and France spent only seven percent.




Jason Davidson is Professor of Political Science and International Affairs at the University of Mary Washington. Email:

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This article originally appeared on Transcend Media Service (TMS) on 17 May 2021.

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