As I interpret this GAO report (this link is the summary), companies make money from DOD contracts, stiff the federal government on taxes, and keep getting contracts - and DOD doesn't seem to care very much until the GAO says they should get with the program. Stimulating action is, of course, one of the roles of the GAO, but given the Halliburton overcharging I was intrigued to see another example of money just being thrown away by DOD.