There is no definitive estimate of their total since the costs go well beyond purely military budgets, but Linda Bilmes of Harvard University and Joseph Stiglitz of Columbia University described it in the title of their book in 2008 as the Three Trillion Dollar War, which Stiglitz updated in a 2015 interview as a total cost of $5 trillion–$7 trillion – which can be compared with the US’s annual GDP which is now more than $18 trillion.
