In early 2003, as war fever built in Washington, an Iraqi scientist faced a fateful choice.

Rihab Rashid Taha (search) could try to lower the heat by finally telling U.N. inspectors what happened to Iraq's "missing" anthrax.

Or she could remain silent, rather than risk Saddam Hussein's (search) wrath.

The microbiologist's dilemma, she has told U.S. interrogators, was that her team 12 years earlier had destroyed the lethal bacteria by dumping it practically at the gates of one of Saddam's main palaces, and the feared Iraqi despot might grow enraged at news of anthrax on his doorstep.

Taha chose silence in 2003, thus stoking suspicions of those who contended Iraq still harbored biological weapons. Soon thereafter, two years ago this month, the United States invaded.

"Whether those involved understood the significance and disastrous consequences of their actions is unclear," the CIA-ledIraq Survey Group (search) says of Taha and colleagues in its final report on Iraq weapons-hunting. "These efforts demonstrate the problems that existed on both sides in establishing the truth."

It also demonstrates anew that the war was launched on the basis not of hard fact, but of speculation and untruths, especially about Iraqi motives and actions.

"We ourselves had a lesson to learn there," one ex-arms inspector, Australian microbiologist Rod Barton, says of the account by Taha, still in U.S. detention in Iraq.

The anthrax mystery had bedeviled U.N. inspectors since the 1990s.

The Iraqis claimed then that before the 1991 Gulf War they had made 2,191 gallons of anthrax, considered highly suited for biowarfare because its spores are relatively easily produced, durable and deadly when inhaled. They said they destroyed all of it in mid-1991 at their bioweapons center at Hakam, 50 miles southwest of Baghdad.

The U.N. experts, who scoured Iraq for banned arms from 1991-98 and again in 2002-03, confirmed anthrax had been dumped at Hakam. But they also found evidence indicating Iraq produced an additional, undeclared 1,800 gallons of anthrax.

In early 2003, chief inspector Hans Blix put the seeming discrepancy high on his list of Iraq's "unresolved disarmament issues," complaining the Iraqis must be withholding information. Colin Powell dwelled on an anthrax threat in his February 2003 speech seeking U.N. Security Council authority for war.

Warning of "tens of thousands of teaspoons" of anthrax still in Iraq, the then-U.S. secretary of state said of the discrepancy, "This is evidence, not conjecture. This is true."

But the truth appears to lie elsewhere, according to the account disclosed in a little-noted section of the Iraq Survey Group report, a 350,000-word document issued last Oct. 6.

The British-educated Taha, who ran the Hakam complex in the 1980s, told interrogators her staff carted off anthrax from Hakam in April 1991 and stored it in a bungalow near the presidential palace at Radwaniyah, 20 miles west of Baghdad, the U.S. teams report.

Later that year the crew dumped the chemically deactivated anthrax on grounds surrounded by a Special Republican Guard barracks near the palace, the report says. Barton, who took part in Iraq Survey Group interrogations, said in a recent Australian Broadcasting Corp. interview that the disposal was carried out in July 1991 when Iraqi orders came down to destroy all bioweapons agents immediately.

Then, through the years, Taha and other Iraqi officials denied the "missing" anthrax ever existed.

"The members of the program were too scared to tell the Regime that they had dumped deactivated anthrax within sight of one of the principal presidential palaces," the Iraq Survey Group says.

The arms hunters' report also concludes, "ISG's investigation found no evidence that Iraq continued to hide BW (biological) weapons after the unilateral destruction of 1991 was complete."

"We knew there was a lie," Barton said, "but we jumped to the wrong conclusions."

The U.N. inspection agency says in an assessment of the U.S. report that the Taha disclosure is "perhaps the most significant new information" in the biological area. It suggested sampling and analysis at the Radwaniyah site to corroborate her account.