From the article:

  > At first glance adjustments totaling trillions may seem impossible. The amounts dwarf the
  > Defense Department’s entire budget. Making changes to one account also require making 
  > changes to multiple levels of sub-accounts, however. That created a domino effect where,
  > essentially, falsifications kept falling down the line. In many instances this daisy-chain
  > was repeated multiple times for the same accounting item.