A mass of paper will be airlifted from Baghdad to New York this weekend, a document of thousands of pages whose dull recitation of chemical processes and medical research may help set the course of war and peace in this part of the world.

Soon after that Iraqi weapons "declaration" lands at its headquarters, the United Nations' arms inspectors will be looking for a few pages more, this time from another capital — Washington.

"It will be the moment," says chief inspector Hans Blix, "for those who say they have evidence to put this evidence on the table."

The evidence sought is evidence of Iraqi doomsday weapons. Those who say they have it are the Bush administration. And the moment is one that has been long in coming, U.N. officials believe.

The "accurate, full, and complete declaration" demanded of Iraq by the United Nations this weekend is expected to run to some 13,000 pages.

It will probably include a history of U.N. dismantlement of Iraqi chemical, biological and nuclear weapons programs in the 1990s, and a detailing of current industrial activity in those areas — so-called "dual use" facilities that produce, for example, chlorine for water purification but that could be diverted to making deadly chemical arms.

It also will include, the Iraqis make clear, a rejection of U.S. allegations they still hold weapons of mass destruction. That charge is a "hoax," a pretext for Washington to wage another war against Iraq, says Tariq Aziz, deputy prime minister.

The U.N. inspectors don't accept that.

They took up the weapons hunt again last week, four years after the old U.N. monitoring regime collapsed. Their working assumption is that their predecessors missed some chemical and biological weapons in seven years of inspections and demolition of arms and manufacturing equipment following Baghdad's defeat in the 1991 Gulf War.

The new inspectors have an extensive checklist of open questions they hope this weekend's declaration will address. Just three examples:

—They want evidence Iraq destroyed all components, especially combustion chamber assemblies, for Iraqi-made missiles with a range surpassing 90 miles, a U.N.-set limit.

—Iraq must show convincingly what happened to 550 artillery shells loaded with the powerful chemical agent for mustard gas, munitions Iraq said were lost after the Gulf War.

—Earlier inspectors found the Iraqis deficient in accounting for all purchases and production of biological agents for weapons.

To dispel uncertainty, such things "must be convincingly shown by documentation, by evidence," Blix told reporters in Baghdad last month. "The production of mustard gas is not like the production of marmalade. You must keep track of what you produced."

Washington betrays no uncertainties about Iraq's arsenal.

"We're sure they have in their possession weapons of mass destruction," Secretary of State Colin Powell said Wednesday.

Such certainty is not found in the only recent U.S. intelligence report made public on the subject. That Oct. 4 report and a similar British dossier are full of "probablys," "mays" and "coulds" attached to their allegations.

Satellite photos, for example, show new construction at sites formerly associated with major arms programs, and the CIA report suggested the Iraqis may have resumed production of banned weapons there. But in their first week back in Iraq, the U.N. inspectors have surveyed at least two of these complexes and have not reported any startling finds.

In another example, the CIA summary says Iraq has sought to buy thousands of high-strength aluminum tubes that "most intelligence specialists" believe are intended as core cylinders for centrifuges Iraq would use to enrich uranium for nuclear bombs.

But some experts believe the tubes were more likely destined for non-nuclear uses, and this week a senior Iraqi official showed off aluminum tubes to reporters at a plant where they were used for making small artillery rockets.

The International Atomic Energy Agency, whose specialists are among the inspectors, said last month it had asked for more solid evidence on the tubes from the U.S. government. There's no word it has been received, however.

"I believe that we are not being served the intelligence that national authorities have," Blix's deputy, Demetrius Perricos, said Wednesday in Baghdad. He then flew back to their New York U.N. headquarters to await the Iraqi declaration and, he said, to see what intelligence, if any, the United States might now provide to help the weapons hunt.

The White House on Thursday said it would offer the United Nations "solid" evidence, but again declined to say what that might be. Instead, Bush administration officials were telling reporters that Iraq's weekend declaration may prove so patently false, in their view, that they'll move straightaway for U.N. Security Council approval of military action. Failing that, they said, the United States might attack Iraq on its own.

In Baghdad, the U.N. inspectors, currently numbering just two dozen, talk of patience. Their numbers will multiply in the coming days, and their work is planned to stretch over months, and then to years of long-term, fixed monitoring of Iraq's military-industrial complex.

"This is not a one-week wonder," their top boss, Kofi Annan, said in New York on Tuesday. "This is only a beginning," the U.N. secretary-general said — if events don't intervene first.