The U.S. government has reportedly poured as much as $2.8 trillion into the fight against terrorism since the Sept. 11, 2001, terrorist attacks, but some of that spending may have been unnecessary, according to a new study. The Stimson Center, a Washington-based think tank, said that figure includes both military spending in Afghanistan, Iraq, and Syria, and homeland security efforts in the U.S. and overseas. But with no transparency in the current system for counter-terrorism spending, billions may have been spent on items that didn’t warrant emergency funding, according to the study. “The Stimson study group found a variety of weaknesses in definitions, tracking, and consistencies that limit accuracy and contribute to a lack of transparency regarding the current data,” the study said. Those “weaknesses” make it impossible to assess whether all the spending has been “effective,” the study’s authors say. Counter-terrorism spending is now 10 times higher than it was prior to 9/11, and the White House Office of Management and Budget’s annual report tracking such spending was discontinued this year.