It’s common knowledge the wars in Afghanistan and Iraq have cost the American taxpayer an exorbitant amount of money. The U.S. government’s lack of transparency to determine the true expense fuels wild speculations.

So far, estimates vary between $1 and $2 trillion. Since there are so many different agencies and departments involved makes it even harder to pinpoint an accurate number. However, a recent study by the Center for Strategic and International Studies (CSIS) reveals these estimations might be excessively conservative, and the true cost might amount to almost $6 trillion.

The CSIS report examines the FY2001-FY2019 time frame and all military and civilian funds allocated to fight or support the Afghanistan and Iraq war efforts. Report authors credibly present costs of up to $2.1 trillion–but this amount doesn’t include numerous programs and projects. The authors project actual costs of $5.9 trillion, and predict by the end of FY2023,  the outlay will reach $6.7 trillion.

Additionally, the CSIS report calculations account for direct and indirect costs. For example, funds spent by the U.S. State Department for foreign aid, or the Department of Veteran Affairs for veterans’ support.

But the Department of Defense’s (DoD) budget isn’t affected by the costs of war. Instead, to cover these protracted conflicts, the DoD receives considerable funding every year. According to the CSIS report, during the FY2001-FY2019 span, these additional appropriations total approximately $2.2 trillion, or about 20 percent of all defense spending for the same time period. Roughly 98 percent of funding goes to support Global War on Terror operations, which aren’t limited to Afghanistan and Iraq.

“There is a clear need for better reporting on the cost of America’s wars,” concludes the analysis. “Such reporting should be unclassified, fully defined, and explain what costs are and are not included. It should tie such spending to levels of effectiveness, and to an estimate of whether U.S. strategy, plans, and budgets can end in some form of meaningful victory. The Executive branch should provide regular reporting on the cost and level of success for each war, and the Congress should openly debate both the rising cost of America’s wars and the adequacy of U.S. strategy and operations.”

Moreover, the report points to a hesitance by successive administrations and Congressional oversight committees to transparently discuss the actual costs of the wars. A reason behind this lack of willingness for debate may be the ineffectiveness of expensive programs.