Through Fiscal Year 2020, the United States federal government has spent or obligated $6.4 trillion dollars on the post-9/11 wars in Afghanistan, Pakistan, Iraq, and elsewhere. This figure includes: direct Congressional war appropriations; war-related increases to the Pentagon base budget; veterans care and disability; increases in the homeland security budget; interest payments on direct war borrowing; foreign assistance spending; and estimated future obligations for veterans’ care.
This total omits many other expenses, such as the macroeconomic costs to the US economy; the opportunity costs of not investing war dollars in alternative sectors; future interest on war borrowing; and local government and private war costs.
Public access to budget information about the post-9/11 is imperfect and incomplete. The scale of spending alone makes it hard to grasp. Public understanding of the budgetary costs of war is further limited by secrecy, faulty accounting, and the deferral of current costs.
The current wars have been paid for almost entirely by borrowing. This borrowing has raised the US budget deficit, increased the national debt, and had other macroeconomic
— source Watson Institute | Jul 2021