Earlier this year, a Michigan State University economist, working with graduate students and a former government official, found $21 trillion in unauthorized spending in the departments of Defense and Housing and Urban Development for the years 1998-2015.
The work of Mark Skidmore and his team, which included digging into government websites and repeated queries to U.S. agencies that went unanswered, coincided with the Office of Inspector General, at one point, disabling the links to all key documents showing the unsupported spending. (Luckily, the researchers downloaded and stored the documents.)
Now, the Department of Defense has announced it will conduct the first department-wide, independent financial audit in its history (read the Dec. 7 announcement here).
The Defense Department did not say specifically what led to the audit. But the announcement came four days after Skidmore discussed his team’s findings on USAWatchdog, a news outlet run by former CNN and ABC News correspondent Greg Hunter.
http://msutoday.msu.edu/news/2017/msu-scholars-find-21-trillion-in-unauthorized-government-spending-defense-department-to-conduct/

Missing Trillions

Rumsfeld Buries Admission of Missing 2+ Trillion Dollars in 9/10/01 Press Conference

On September 10, 2001, Secretary of Defense Donald Rumsfeld held a press conference to disclose that over $2,000,000,000,000 in Pentagon funds could not be accounted for. Rumsfeld stated: “According to some estimates we cannot track $2.3 trillion in transactions.” According to a report by the Inspector General, the Pentagon cannot account for 25 percent of what it spends. ^1   2 
http://911research.wtc7.net/sept11/trillions.html