Yesterday in the Intenational Herald Tribune:

‘The Pentagon cannot account for 190,000 AK-47 rifles and pistols given to Iraqi security forces in 2004 and 2005, or about half the weapons earmarked for soldiers and police officers, according to a government report.
The Government Accountability Office, the investigative arm of Congress, said in a July 31 report to lawmakers that the Defense Department also could not account for 135,000 pieces of body armor and 115,000 helmets reported to have been issued to Iraqi forces as of Sept. 22, 2005.
The congressional office said the Pentagon concurred with its findings and had begun a review to ensure full accountability for the program to train and equip Iraqi forces.
"Our review of the 2007 property books found continuing problems with missing and incomplete records," the report said.
The report raised concerns that weapons provided by the United States could be falling into the hands of insurgents and criminals. A senior Pentagon official told The Washington Post that some of the weapons probably were being used against American troops.’

How exactly do they know that these weapons cannot be accounted for?

Maybe Iraqi soldiers are selling their weapons to make a living? Sort of.