U.S. and European governments have imposed economic sanctions on Iran in response to Tehran's nuclear program.
An 11-page report from the Special Inspector General for Afghanistan Reconstruction finds that "limited visibility" over imports of fuel into Afghanistan increases that risk that the U.S. military may have violated economic sanctions against Iran.
The report states that the Defense Department's lack of oversight on fuel purchased for the Afghan National Security Force raises serious concerns.
"(Department of Defense) lacked certification procedures prior to November 2012 and had limited visibility over the import and delivery sub-contracts used by fuel vendors," the report states. "As a result, (Department of Defense) is unable to determine if any of the $1.1 billion in fuel purchased for the ANA between fiscal year 2007 and 2012 came from Iran, in violation of U.S. economic sanctions."
The SIGIR report states that the United States appropriated about $47.7 billion of taxpayer money into the fund for Afghan forces between fiscal years 2007 and 2012.
There was no immediate reaction to the SIGIR report from the White House or Defense Department.