$1 billion shady expenses on contractors in Afghanistan

The Defense Contract Audit Agency has examined $5.9 billion in Afghanistan troop support contracts and determined that $950 million of the expenses were unreasonable or lacked adequate documentation to support them, according to a memo prepared by McCaskill's staff and distributed to subcommittee members.

"That's nearly one of every six dollars," she said.

The growing number of contractors in Afghanistan is outpacing the ability to oversee them, raising concerns that the waste and fraud that marred the U.S. mission in Iraq will be repeated, lawmakers said Thursday.

Sen. Claire McCaskill, D-Mo., said there are already more than 100,000 Defense Department contractors in Afghanistan and that figure could grow to 160,000 to support the surge of U.S. troops ordered by President Barack Obama earlier this month.