As of August 2016, the US has already appropriated, spent, or taken on obligations to spend more than $3.6 trillion in current dollars on the wars in Iraq, Afghanistan, Pakistan and Syria and on Homeland Security (2001 through fiscal year 2016). To this total should be added the approximately $65 billion in dedicated war spending the Department of Defense and State Department have requested for the next fiscal year, 2017, along with an additional nearly $32 billion requested for the Department of Homeland Security in 2017, and estimated spending on veterans in future years. When those are included, the total US budgetary cost of the wars reaches $4.79 trillion.
Interest costs for overseas contingency operations spending alone are projected to add more than $1 trillion dollars to the national debt by 2023. By 2053, interest costs will be at least $7.9 trillion unless the US changes the way it pays for the wars