By FY2015, Congress appropriated almost $1.6 trillion dollars to the Pentagon for the wars in Afghanistan, Pakistan, and Iraq.
Unfortunately, because the Pentagon has not done a competent or transparent accounting for these and other appropriations, we have no reliable assurance of how, or even where, the funds were actually spent.
In addition, Pentagon managers and Congress permitted appropriations ostensibly for the wars to actually address expenses that were only marginally related to those wars. For this reason and because some expenses in Department of Defense (DOD) appropriations not earmarked for the Iraq and Afghanistan wars were induced by the wars, the actual amounts of all war expenses might come to a significantly different total.
The DOD “base” budget grew over the discernible pre-war 2001 plan for Pentagon spending by approximately $836 billion in current dollars in the period from 2001 through FY2014. This additional spending is most plausibly explained by the political dynamics of the post-9/11 wars that translated into Congressional support, not just for war funding, but for the broader DOD budget as well. It should be counted as an additional, albeit indirect, cost of the wars and included in any comprehensive attempt to capture the total cost of the wars.
Pentagon accounting for the wars has been deeply inadequate, and we do not know what the DOD actually spent on the wars.
The best accounting of Pentagon appropriations is by the Congressional Research Service, showing $1.6 trillion through FY2015.
Congress should require the Department of Defense Inspector General to conduct a comprehensive audit of the actual amounts of all federal funding spent on the post-9/11 wars, and should make the report publicly available.
(Page updated as of February 2015)