The US-led coalition in Iraq has failed to deliver nearly two-thirds of the equipment it promised to Iraq's army, the US Defence Department has said.
Iraqi troops have been frustrated by delays in receiving equipment
The Pentagon said only 14.5m of the nearly 40m items of equipment ordered by the Iraqi army had been provided.
The US military commander in charge of training in Iraq has asked for help in speeding up the transfer of equipment.
On Wednesday, Iraq's ambassador to the US said the delays were hindering the fighting capacity of its armed forces.
Samir Sumaidaie said Iraqi troops were often "cannon fodder" for militants.
"There is general frustration in the Iraqi government at the rate at which Iraqi armed forces are being equipped and armed," he said.
"This is a collaborative effort between the Iraqi government and the government of the United States, and the process is not moving quickly enough to improve the fighting capacity of Iraqi armed forces."
"A way must be found to improve this process."
The Pentagon said it was doing all it could to send out the items, with priority given to equipment that can be used for counter-insurgency.
It said some deliveries had been delayed by the export licensing process, while others had been affected by changes in orders.
"We share a common goal with the Iraqis that their forces should be equipped with the type of things that they need to include force protection equipment, mobility equipment, communications equipment," Bryan Whitman, a spokesman for the Pentagon, said.
"But it's a challenge. You can't do it overnight."
The chairman of the Joint Chiefs of Staff, Gen Peter Pace, has promised to work on delivering the equipment to the Iraqi forces more quickly.
Last week, Gen Pace was asked by Lt Gen James Dubik, who oversees the training of Iraqi forces, for help in improving the system.
Meanwhile, the latest BBC survey of casualties in Iraq has shown that 416 people were killed in the week ending on Wednesday.
The figure is down considerably on the previous week.
A US military commander in Iraq, Lt Gen Ray Odierno expressed cautious optimism at a slowing in US casualties, but said attacks on the heavily-fortified Green Zone in Baghdad seemed to be getting more accurate.
The survey is intended to assess the effects of the surge of American troops in Iraq. It is based on figures provided by the US and Iraqi authorities.