Vienna, Austria ? Revelations that nearly 400 tons of conventional explosives have disappeared in Iraq have experts worrying that other weapons might also be in jeopardy of falling into insurgent or terrorist hands.

Even the State Department concedes it can’t provide “100 percent security for 100 percent of the sites.” And by all accounts, Iraq is studded with weapons depots — many in places where U.S.-led forces are preoccupied by fierce fighting.

Troubling questions about which other weapons could be vulnerable to looting have arisen since the U.N. nuclear agency’s warning this week that 377 tons of non-nuclear explosives vanished from the former Al-Qaqaa military installation south of Baghdad.

International Atomic Energy Agency spokeswoman Melissa Fleming said Tuesday that the Iraqis had not told the IAEA about any other missing materials since their Oct. 10 letter stating that the weapons vanished from Al-Qaqaa as a result of “theft and looting … due to lack of security” sometime after coalition forces took control of the capital.

But she said the agency’s chief Iraq inspector, Jacques Baute, “would encourage more such reporting on what has happened to sites subject to IAEA verification.” IAEA chief Mohamed ElBaradei reported the explosives’ disappearance to the U.N. Security Council on Monday.

Military ‘failure’

Regarding the inaction on the part of the United States, “There was an utter lack of curiosity to follow up on what was well-known to the U.N.,” said David Albright, a former U.N. weapons inspector.

“There was a systematic failure of the military, which overran the country and left all these explosives behind without protecting its rear,” he said. “The military should have had the sense to either secure high explosives and armaments or blow them up as they went through.”

The Al-Qaqaa explosives included HMX and RDX, key components in plastic explosives, which insurgents in Iraq have used in repeated bomb attacks on the U.S.-led multinational force.

No orders to search

One of the first U.S. military units to reach the Al-Qaqaa military installation south of Baghdad after the invasion of Iraq did not have orders to search for the nearly 400 tons of explosives that are missing from the site, the unit spokesman said Tuesday.

When troops from the 101st Airborne Division’s 2nd Brigade arrived at the Al-Qaqaa base a day or so after other coalition troops seized Baghdad on April 9, 2003, there were already looters throughout the facility, Lt. Col. Fred Wellman, deputy public affairs officer for the unit, told The Associated Press.

The soldiers “secured the area they were in and looked in a limited amount of bunkers to ensure chemical weapons were not present in their area,” Wellman wrote in an e-mail message to The Associated Press. “Bombs were found but not chemical weapons in that immediate area.

“Orders were not given from higher to search or to secure the facility or to search for HE type munitions, as they (high-explosive weapons) were everywhere in Iraq,” he wrote.

While Wellman said the 101st Airborne troops were the first at Al-Qaqaa after the U.S.-led invasion, NBC News reported Tuesday night that Army 3rd Infantry Division troops arrived several days earlier.

Quoting unidentified Army officials, NBC said 3rd Infantry soldiers got to the weapons complex April 4, finding “looters everywhere” carrying what they could out on their backs.

Associated Press Correspondent Chris Tomlinson, who also was embedded with the 3rd Infantry, described the search of Iraqi military facilities south of Baghdad as brief, cursory missions to seek out hostile troops, not to inventory or secure weapons stockpiles. One task force, he said, searched four Iraqi military bases in a single day, meeting no resistance and finding only abandoned buildings, some containing weapons and ammunition.

The enormous size of the bases, the rapid pace of the advance on Baghdad and the limited number of troops involved, made it impossible for U.S. commanders to allocate any soldiers to guard any of the facilities after making an initial check, Tomlinson said. The task force he was traveling with didn’t go to Al-Qaqaa.

NBC said that with more than 1,000 buildings, the Al-Qaqaa complex was so large that it was not clear the troops even saw the bunkers that might have held the explosives.

Pentagon officials could not be reached to comment on the NBC account.