A rear door gunner on a CH-47, keeps watch on the mountains in Uruzgan province, Afghanistan, May 12, 2013.

WASHINGTON — American taxpayers have spent $6.4 trillion on post-9/11 wars and military action in the Middle East and Asia, according to a new study.

That total is $2 trillion more than the entire federal government spending during the recently completed 2019 fiscal year. The U.S. government spent $4.4 trillion during the fiscal year that ended Sept. 30, according to the Treasury Department.

The report, from the Watson Institute of International and Public Affairs at Brown University, also finds that more than 801,000 people have died as a direct result of fighting. Of those, more than 335,000 have been civilians. Another 21 million people have been displaced due to violence.

The report comes as the Trump administration works to withdraw the U.S. military presence from war-torn Syria. Last year, President Donald Trump went through a similar debate over whether to withdraw U.S. troops from Afghanistan, ultimately agreeing to keep them there but only after repeatedly raising questions about why they should stay.

The $6.4 trillion figure reflects the cost across the U.S. federal government since the price of America's wars is not borne by the Defense Department alone, according to Neta Crawford, who authored the study.

Crawford explains that the post-9/11 wars in Iraq, Afghanistan, Pakistan and Syria have expanded to more than 80 countries — "becoming a truly global war on terror."

The longer wars drag on, more and more service members will ultimately claim veterans benefits and disability payments, the study points out.

"Even if the United States withdraws completely from the major war zones by the end of FY2020 and halts its other Global War on Terror operations, in the Philippines and Africa for example, the total budgetary burden of the post-9/11 wars will continue to rise as the U.S. pays the on-going costs of veterans' care and for interest on borrowing to pay for the wars," Crawford writes.

In March, the Pentagon estimated that the wars in Afghanistan, Iraq and Syria have cost each taxpayer $7,623 through fiscal 2018.