When President Bush traveled to the United Nations in September to make his case against Iraq, he brought along a rare piece of evidence for what he called Iraq's "continued appetite" for nuclear bombs. The finding: Iraq had tried to buy thousands of high-strength aluminum tubes, which Bush said were "used to enrich uranium for a nuclear weapon."
Bush cited the aluminum tubes in his speech before the U.N. General Assembly and in documents presented to U.N. leaders. Vice President Cheney and national security adviser Condoleezza Rice both repeated the claim, with Rice describing the tubes as "only really suited for nuclear weapons programs."
It was by far the most prominent, detailed assertion by the White House of recent Iraqi efforts to acquire nuclear weapons. But according to government officials and weapons experts, the claim now appears to be seriously in doubt.
After weeks of investigation, U.N. weapons inspectors in Iraq are increasingly confident that the aluminum tubes were never meant for enriching uranium, according to officials familiar with the inspection process. The International Atomic Energy Agency (IAEA), the U.N.-chartered nuclear watchdog, reported in a Jan. 8 preliminary assessment that the tubes were "not directly suitable" for uranium enrichment but were "consistent" with making ordinary artillery rockets -- a finding that meshed with Iraq's official explanation for the tubes. New evidence supporting that conclusion has been gathered in recent weeks and will be presented to the U.N. Security Council in a report due to be released on Monday, the officials said.
Moreover, there were clues from the beginning that should have raised doubts about claims that the tubes were part of a secret Iraqi nuclear weapons program, according to U.S. and international experts on uranium enrichment. The quantity and specifications of the tubes -- narrow, silver cylinders measuring 81 millimeters in diameter and about a meter in length -- made them ill-suited to enrich uranium without extensive modification, the experts said.
But they are a perfect fit for a well-documented 81mm conventional rocket program in place for two decades. Iraq imported the same aluminum tubes for rockets in the 1980s. The new tubes it tried to purchase actually bear an inscription that includes the word "rocket," according to one official who examined them.
"It may be technically possible that the tubes could be used to enrich uranium," said one expert familiar with the investigation of Iraq's attempted acquisition. "But you'd have to believe that Iraq deliberately ordered the wrong stock and intended to spend a great deal of time and money reworking each piece."
As the U.N. inspections continue, some weapons experts said the aluminum tubes saga could undermine the credibility of claims about Iraq's arsenal. To date, the Bush administration has declined to release photos or other specific evidence to bolster its contention that Iraq is actively seeking to acquire new biological, chemical and nuclear arms, and the means to deliver them.
The U.N. inspections earlier this month turned up 16 empty chemical warheads for short-range, 122mm rockets. But inspectors said that so far they have found no conclusive proof of a new Iraqi effort to acquire weapons of mass destruction in searches of facilities that had been identified as suspicious in U.S. and British intelligence reports. U.N. officials contend that Iraq retains biological and chemical weapons and components it acquired before the 1991 Persian Gulf War.
"If the U.S. government puts out bad information it runs a risk of undermining the good information it possesses," said David Albright, a former IAEA weapons inspector who has investigated Iraq's past nuclear programs extensively. "In this case, I fear that the information was put out there for a short-term political goal: to convince people that Saddam Hussein is close to acquiring nuclear weapons."
The Bush administration, while acknowledging the IAEA's findings on the aluminum tubes, has not retreated from its earlier statements. White House spokesman Ari Fleischer reacted to the IAEA's initial report on Jan. 8 by asserting that the case was still open.
"It should be noted," Fleischer said, "that the attempted acquisition of such tubes is prohibited under the United Nations resolutions in any case." U.N. sanctions restrict Iraq's ability to import "dual-use" items that potentially could be used for weapons.
U.S. intelligence officials contend that the evidence, on balance, still points to a secret uranium enrichment program, although there is significant disagreement within the intelligence services. Those supporting the nuclear theory said they were influenced by "other intelligence" beyond the specifications of the tubes themselves, according to one intelligence official. He did not elaborate.
IAEA officials said the investigation of the tubes officially remains open. Earlier this week, Iraq agreed to provide inspectors with additional data about its intended use for the tubes.
The controversy stems from a series of Iraqi attempts to purchase large quantities -- thousands or tens of thousands -- of high-strength aluminum tubes over the last two years. Apparently none of the attempts succeeded, although in one instance in 2001 a shipment of more than 60,000 Chinese-made aluminum tubes made it as far as Jordan before it was intercepted, according to officials familiar with Iraq's procurement attempts.
Since then, the officials said, Iraq has made at least two other attempts to acquire the tubes. The more recent attempts involved private firms located in what was described only as a "NATO country." In all, more than 120,000 of the tubes were reportedly sought.
In each of the attempts, Iraq requested tubes made of an aluminum alloy with precise dimensions and high tolerances for heat and stress. To intelligence analysts, the requests had a ring of familiarity: Iraq had imported aluminum tubes in the 1980s, although with different specifications and much larger diameter, to build gas centrifuges -- fast-spinning machines used in enriching uranium for nuclear weapons. Through a crash nuclear program launched in 1990, Iraq succeeded in enriching nearly enough uranium for one bomb before its plans were disrupted in 1991 by the start of the Gulf War, according to U.N. weapons inspectors.
By several accounts, Iraq's recent attempts to buy aluminum tubes sparked a rancorous debate as Bush administration officials, intelligence analysts and government scientists argued over Iraq's intent.
"A number of people argued that the tubes could not possibly be used as artillery rockets because the specifications were so precise. It would be a waste of dollars," said one knowledgeable scientist.
Ultimately, the conclusion in the intelligence discussion was that Iraq was planning to use the tubes in a nuclear program. This view was favored by CIA analysts. However, there were dissenting arguments by enrichment experts at the Energy Department and officials at the State Department. What ultimately swung the argument in favor of the nuclear theory was the observation that Iraq had attempted to purchase aluminum tubes with such precise specifications that it made other uses seem unlikely, officials said.
By contrast, in Britain, the government of Prime Minister Tony Blair said in a Sept. 24 white paper that there was "no definitive intelligence" that the tubes were destined for a nuclear program.
The tubes were made of an aluminum-zinc alloy known as 7000-series, which is used in a wide range of industrial applications. But the dimensions and technical features, such as metal thickness and surface coatings, made them an unlikely choice for centrifuges, several nuclear experts said. Iraq used a different aluminum alloy in its centrifuges in the 1980s before switching to more advanced metals known as maraging steel and carbon fibers, which are better suited for the task, the experts said.
Significantly, there is no evidence so far that Iraq sought other materials required for centrifuges, such as motors, metal caps and special magnets, U.S. and international officials said.
Bush's remarks about the aluminum tubes caused a stir at the IAEA's headquarters in Vienna. Weapons experts at the agency had also been monitoring Iraq's attempts to buy the aluminum but were skeptical of arguments that the tubes had a nuclear purpose, according to one official who spoke on the condition of anonymity. The IAEA spent seven years in the 1990s documenting and ultimately destroying all known vestiges of Iraq's nuclear weapons program, including its gas centrifuges.
After returning to Iraq when weapons inspections resumed in November, the IAEA made it a priority to sort out the conflicting claims, according to officials familiar with the probe. In December, the agency spent several days poring through files and interviewing people involved in the attempted acquisition of the tubes -- including officials at the company that supplied the metal and managers of the Baghdad importing firm that apparently had been set up as a front company to acquire special parts and materials for Iraq's Ministry of Industry. According to informed officials, the IAEA concluded Iraq had indeed been running a secret procurement operation, but the intended beneficiary was not Iraq's Atomic Energy Commission; rather, it was an established army program to replace Iraq's aging arsenal of conventional 81mm rockets, the type used in multiple rocket launchers.
The explanation made sense for several reasons, they said. In the 1980s, Iraq was known to have obtained a design for 81mm rockets through reverse-engineering of munitions it had previously purchased abroad. During the Iran-Iraq war, Iraqis built tens of thousands of such rockets, using high-strength, 7000-series aluminum tubes it bought from foreign suppliers. U.N. inspectors in the 1990s had allowed Iraq to retain a stockpile of about 160,000 of the 81mm rockets, and an inspection of the stockpile last month confirmed that the rockets still exist, though now corroded after years of exposure in outdoor depots.
By all appearances, the Iraqis were "trying to buy exact replacements for those rockets," said Albright, the former IAEA inspector.
Albright, now president of the Institute for Science and International Security, a Washington research group, said that even a less sinister explanation for the aluminum tubes did not suggest Iraq is entirely innocent.
"But if Iraq does have a centrifuge program, it is well-hidden, and it is important for us to come up with information that will help us find it," Albright said. "This incident discredits that effort at a time when we can least afford it."
Staff writer Walter Pincus contributed to this report.