The facility, known as Location C, was Iraq's only internationally sanctioned storage site for nuclear material. It thus was a potential prize for U.S. forces - or for anyone seeking to steal radioactive material for sale to other countries or to terrorists.
Iraqi Republican Guard troops abandoned the site late last week as U.S. forces approached the nearby Tuwaitha nuclear research center south of Baghdad. Looters soon cut Tuwaitha's electric fences and began ransacking homes and offices, hauling off televisions and carpets in stolen luxury cars.
Initial reports indicate that U.S. Marines who entered the complex last weekend did not realize Tuwaitha's significance. Nor did they immediately look for the nuclear warehouses about a mile away.
Marine combat engineers finally secured Location C on Wednesday after a State Department counterterrorism task force warned Central Command of the danger, U.S. officials said.
It was not clear yesterday whether special U.S. weapons teams had reached the site. Officials at the Pentagon and in Qatar said they did not know if anyone had breached the steel doors and removed any of the 500 tons of unrefined uranium and uranium dioxide, 1.8 tons of low-enriched uranium and 150 transportable radioactive devices from Iraqi hospitals and research facilities that were stored at the site.
"The most immediate concern is the radioactive isotopes," said David Albright, a former nuclear weapons inspector in Iraq who now heads the nonprofit Institute for Science and International Security in Washington. "You worry that some idiot will take them and spread them around. We don't need a radiation accident. Or that someone will try to sell them for a dirty bomb. Or that they'll try to sell the uranium on the black market for someone else's nuclear weapons program."
Experts say the security lapse also points to a larger concern: the immediate need to find and protect Iraq's nuclear weapons blueprints, ballistic missile manuals, precursor chemicals for nerve gases, microbe feeder stocks for germ weapons and countless other potentially dangerous materials that could supply terrorists or illegal weapons programs around the world.
"There's a tremendous danger that materials could slip out of the country," warned Rolf Ekeus, who headed United Nations arms inspections teams in Iraq in the 1990s. "It's very important that these sites be taken under control immediately."
Another problem: the 3,000 or so Iraqi scientists, military officers and engineers who provided the intellectual heft, technical expertise and command structure for Saddam Hussein's clandestine weapons production and procurement systems, according to U.N. records. None has yet been interrogated.
Experts warn that Iraq's weapons designers may flee the country and offer their services to other rogue regimes before they can be rounded up. Most of the scientists and engineers at Tuwaitha disappeared.
"There could be a brain drain like we saw after the collapse of the Soviet Union," said Jonathan Tucker, a former U.N. inspector now at the U.S. Institute for Peace in Washington. "These are people with valuable technical know-how. Presumably they're now unemployed. They might be tempted to work for other countries or for al-Qaida."
Bob Drogin writes for the Los Angeles Times, a Tribune Publishing newspaper.