British military personnel were twice as likely to be killed in Afghanistan, when compared to their American counterparts, a new report has suggested.
'The Costs of War to United States Allies Since 9/11', published by Brown University in the United States, compared the death figures between UK and US-allied forces in the Middle Eastern country.
It states British and Canadian personnel "put their lives at risk at twice the rate of American troops".
According to the report, 455 British personnel died in Afghanistan between the start of operations in 2001 and 2017.
The total number of American deaths recorded in the same time period was much higher at 2,316, but proportionally lower compared to the UK once peak deployment figures are considered.
In context, the US lost 2.3% of its personnel in Afghanistan during this period, while the UK lost 4.7%.
A total of 158 Canadian fatalities accounted for 5.4% of peak deployment numbers in the country, the highest in the coalition.
Jason Davidson, who authored the report, said it "demonstrates that allies were there, making real sacrifices" – referencing the contribution of the UN's International Security Assistance Force, established in 2001.
He added that the nature of deployment may have impacted the figures.
Watch: What have British personnel been doing in Afghanistan since 2001?
Mr Davidson suspects a higher proportion of logistical support and command roles in the US forces could have made Americans "less prone" to incurring fatalities during the conflict.
Meanwhile, heavy fighting in Helmand Province saw a large loss of British life during the period.
The Brown University report also highlights the differences in defence spending "as a percentage of its total military expenditure in one year", stating: "The United Kingdom’s 2001-18 military spending on Afghanistan was roughly half the US figure.
"Whereas the US spent over 100% of its baseline on 17 years of its campaign in Afghanistan, the UK spent 56% of its baseline spending in Afghanistan over the same time period."
The report also found that the US suffered greater proportional loss of life in Iraq between March 2003 and January 2012 and made proportionally higher aid contributions to the country between 2013 and 2018.
Britain entered Afghanistan with the US in 2001 after the 9/11 World Trade Center attacks.
In the last 20 years, more than 150,600 UK personnel have served in Afghanistan, although Britain is now set to "drawdown" from the country.
The US has officially started withdrawing troops from Afghanistan and is aiming to complete the drawdown by 11 September – the 20th anniversary of the 9/11 terror attacks.
Under the Trump administration, the US had agreed with the Taliban to withdraw all its troops from Afghanistan by 1 May 2021, but that was pushed back by President Joe Biden in April.