The report, prepared at the request of the chairman of the Senate Armed Services Committee, Virginia Republican John Warner, also found that major challenges remain that put at risk the Defense Department's goal of strengthening Iraqi security forces by transferring all logistics operations to the Defense Ministry by the end of 2007.
A spokesman for Warner said the senator read the report over the weekend in preparation for a meeting Tuesday with Stuart W. Bowen Jr., the Special Inspector General for Iraq Reconstruction.
Warner, who requested the report in May, "believes it is essential that Congress and the American people continue to be kept informed by the inspector general on the equipping and logistical capabilities of the Iraqi army and security forces, since these represent an important component of overall readiness," said Warner spokesman John Ullyot.
The Pentagon cannot account for 14,030 weapons — almost 4 percent of the semiautomatic pistols, assault rifles, machine guns, rocket-propelled grenade launchers and other weapons it began supplying to Iraq since the end of 2003.
The missing weapons will not be tracked easily: The Defense Department registered the serial numbers of only about 10,000 of the 370,251 weapons it provided — less than 3 percent.
Missing from the Defense Department's inventory books were 13,180 semiautomatic pistols, 751 assault rifles and 99 machine guns.
The audit on logistics capabilities said there is a "significant risk" that the Iraqi Interior Ministry "will not be capable of assuming and sustaining logistics support for the Iraqi local and national police forces in the near term." That support includes equipment maintenance, transportation of people and gear and health resources for soldiers and police.
Meanwhile, the U.S. military on Monday announced the death of the 101st servicemember killed in Iraq this month.
In a brief statement, the military said the latest casualty was a member of a police brigade who was killed by small arms fire this morning in eastern Baghdad.
Earlier, a Marine assigned to Regimental Combat Team 5, died from injuries sustained during combat on Sunday, the military said in a brief announcement.
The Marine's name was being withheld pending notification of next of kin.
October is already the fourth deadliest month for American troops since the war began in March 2003. The previous high monthly death tolls were 107 in January 2005; at least 135 in April 2004, and 137 in November 2004, when U.S. forces swept through the insurgent stronghold of Fallujah.
The military said Sunday's death came in Anbar province west of Baghdad, a hotbed of the Sunni resistance to U.S. forces and their Iraqi government allies.
CBS News chief foreign correspondent Lara Logan reports that Anbar has long been the front line of the U.S. military's fight against al Qaeda affiliated militants in Iraq, and, until recently, was one of the most deadly provinces for American forces.
The capital region has taken over as the scene of the overwhelming majority of U.S. troop deaths.
Logan says that one of the factors making life infinitely more difficult for U.S. troops in Iraq is the increasing level of attacks from Shiite militia groups.
Shiite militias — in particular the Mahdi Army, headed by the radical Baghdad-based cleric Muqtada al-Sadr — are taking more and more American and Iraqi lives, as a vicious cycle of attacks and revenge spirals out of control in the country.
In other developments: