A university study of the costs of the post-9/11 wars has put the total at $5.6 trillion, which translates as $23,386 for each taxpayer.
The $5.6 million estimate of the costs from 9/11 through Fiscal Year 2018 was more than triple the Pentagon's estimate of $1.5 trillion, which would work out to $7,740 for each taxpayer, according to the ongoing "Costs of War" project of the Watson Institute of International and Public Affairs at Brown University.
The much higher figures for the wars in Iraq, Syria and Afghanistan were arrived at by factoring in "other war-related costs, including war-related spending by the State Department, the Department of Veterans Affairs, and Homeland Security" and interest on related debt, the report said.
The report said that interest on the borrowing to fund Overseas Contingency Operations, the so-called war budget for Iraq, Syria and Afghanistan, has already amounted to $534 billion.
The costs for the care and disability compensation of post-9/11 veterans have been rising, and the report said that a "conservative" estimate of the costs of veterans care through 2056 was at least $1 trillion.
In 2016, the most recent year for which there are figures, the VA added 87,669 new compensation recipients to their rolls, the report said. In total, more than more than one million post-9/11 veterans now receive some disability compensation from the VA, the report said.
The VA "has been under-capacity to deal with the influx of new veterans who are eligible for services and it has had to grow its staffing levels very quickly -- doubling in size since 2001 to an estimated 356,000 workers in 2017 -- to manage these veterans' care and to reduce a large backlog in processing claims for disability," the report said.
In addition, the "Costs of War" project said that the figures took into account "that every war costs money before, during and after it occurs -- as governments prepare for, wage, and recover from armed conflict by replacing equipment, caring for the wounded and repairing infrastructure destroyed in the fighting."
"Even if the U.S. stopped spending on war at the end of this fiscal year, interest costs alone on borrowing to pay for the wars will continue to grow apace," the report said.
"By 2056, a conservative estimate is that interest costs will be about $8 trillion unless the U.S. changes the way that it pays for the wars," the report said.
A Defense One report on the study quoted Sen. Jack Reed, D-Rhode Island, the ranking member of the Senate Armed Services Committee, as saying that "We have to recognize that we have been borrowing for 16 years to pay for military operations."
It has been the "first time really in history with any major conflict that we have borrowed rather than ask people to contribute to the national defense directly, and the result is we've got this huge fiscal drag."