As U.S. experts began to copy and comb through Iraq's 12,000-page declaration of its weapons of mass destruction program, the Bush administration moved yesterday to assure skittish allies that it does not intend to use the document as a trigger to begin military operations against Iraq, U.S. and foreign officials said.

"We're now on common ground with the administration" in a position of "measured skepticism" but no "crazed or precipitative reactions" about Iraq's contentions that it has no chemical, biological or nuclear weapons programs, said a senior diplomat from one of the five permanent members of the United Nations Security Council.

The Americans have said "they might use it as a piece of the puzzle, but not as a trigger," another diplomat said. "If they want to use it even as a puzzle piece, they have to say why they don't trust the declaration, and whether they are going to give intelligence to disprove it, or ask the inspectors" to verify Iraqi claims.

The reassurances were accompanied by a substantial softening of recent administration predictions that the document will be riddled with lies constituting a material breach of the U.N. resolution that was adopted unanimously last month. "We have not made any conclusions about the declaration," White House spokesman Ari Fleischer said.

"We want to be very deliberate as we move through and look at this document to determine, with the international community, what this indicates about Saddam Hussein and his disarmament," Fleischer said. Although U.S. military preparations for war continue, Fleischer said "the president hopes to avoid" that eventuality. "Combat," he said, "is the last thing this president wants to engage in."

The Iraqi government contends that it has dismantled its weapons of mass destruction programs.

One of only two copies of the declaration provided by Iraq Saturday ended up in U.S. hands yesterday, despite Friday's Security Council decision that U.N. inspectors should review it before it was distributed to governments.

The United States received the document after it persuaded Colombia's U.N. ambassador, the current president of the Security Council, to turn it over. The council's other permanent members -- Britain, France, Russia and China -- acquiesced to the U.S. move.

U.S. officials said their first order of business was to make copies of the voluminous paper document for the other four council members. U.S. intelligence officials spent much of the day transferring the declaration onto CD-ROMs, which the other four began receiving last night. The 10 rotating members of the council will eventually receive versions with sensitive weapons information excised.

The second original copy was retained by the U.N. Monitoring, Verification and Inspection Commission (UNMOVIC) and the Vienna-based International Atomic Energy Agency (IAEA), which are conducting inspections in Iraq. They began their examination of the document yesterday, and made tentative plans to report their initial conclusions to the council on Dec. 19.

U.S. weapons and intelligence experts have been gathered in a central location in the Washington area, most likely CIA headquarters in Langley, to review the document. Divided into sections covering chemical, biological and nuclear weapons, and long-range missiles prohibited by the United Nations, the U.S. copy is to be parceled out in what one White House official called "one-inch squares" to experts in the various fields.

"We don't know what the elephant will look like when we put the pieces together," the official said.

According to informed sources, and an Iraqi-prepared index of the document made available in New York, a major portion of each section repeats the last presentations the Iraqi government made to U.N. inspectors before they withdrew from Iraq in late 1998. The 2,400-page portion on Iraqi's nuclear program, for example, includes about 2,100 pages that initial review indicated was an exact copy of the earlier document.

A separate portion of the nuclear section, totaling about 300 pages and written in Arabic, is labeled as "covering the period from 1991 to 2002" and is divided into segments describing the major departments of the Iraqi Atomic Energy Organization and a list of nuclear facilities. Another portion covers secondary sites, including a series of companies. Additional data supplied by Baghdad on CD-ROMs also has to be integrated into the narrative, sources said.

The 118-page portion of the chemical declaration that details the post-1998 period includes major and secondary sites. An annex of 841 pages is described as listing dual-use facilities that manufacture commercial products but could produce weapons, and all Iraqi commercial chemical plants that are unrelated to prohibited arms facilities.

The 528-page biological declaration is described as containing more than 100 pages of answers to questions raised by inspectors in the procurement and production areas through 1998. The index of the biological update section, with no page numbers given, promises data through 2002, including information on biological research, development and production facilities that are dual-use and those unrelated to bioweapons. A two-part annex containing supporting documents totals 732 pages.

Nearly half of the 1,240-page section on ballistic missiles is said to detail Iraq's missile projects and the status of "current activities." Another 113 pages cover forms and initial designs of systems, with an additional 11 pages on the "relationship" of the missiles with prohibited activities in other fields, likely a reference to missiles designed to carry chemical, biological or nuclear warheads.

Another chapter promises procurement details on 11 missile projects, including relations with other "states, companies, establishments and main suppliers."

As required by last month's resolution, there is a four-page chronological summary on "remotely piloted aircraft," a project inspectors believed might involve an unmanned chemical or biological weapon delivery system.

Only one Security Council member objected to the agreement to turn over the document to the United States. Syria's U.N. ambassador, Mikhail Wehbe, accused Colombian Ambassador Alfonso Valdivieso of breaching council protocol by deciding that only the permanent five members would have access to the entire document. A number of senior administration officials were said to be unhappy at Friday's decision to give the inspectors first crack at the document, as suggested by UNMOVIC Chairman Hans Blix. Saturday morning, U.S. Ambassador John D. Negroponte called Valdivieso to ask that the document be shared with the council's five permanent members.

A close U.S. ally that receives hundreds of millions of dollars in annual U.S. aid, Colombia also consulted with Secretary of State Colin L. Powell. On Sunday night, U.S. diplomats accompanied Valdivieso to Blix's office to inform him of the decision.

Lynch reported from the United Nations. Staff writer Walter Pincus contributed to this report.

U.N. disarmament experts inspect a factory in the Fallujah complex, which has housed chemical and bioweapons programs, northwest of Baghdad.