WASHINGTON - With its refusal to acknowledge any current weapons of mass destruction programs, Saddam Hussein's regime has helped the United States build a case for military confrontation with Iraq - even one with the international stamp of approval many U.S. allies have demanded.

If early impressions of Iraq's weapons declaration are borne out by more careful study, chief United Nations weapons inspector Hans Blix is expected to tell the Security Council on Thursday that the document contains gaps and leaves basic questions unanswered, diplomats say.

This would mark the first step in a process that could lead to a council finding that Iraq is in "material breach" of U.N. mandates and perhaps making Iraq subject to "serious consequences," a diplomatic euphemism for war.

Since September, when President Bush launched his campaign to disarm Iraq, Washington and foreign capitals have reverberated with doubts that the United States would win international approval for a war to oust Hussein. Bush made sure that the council resolution adopted unanimously Nov. 8 left the United States the option of going to war on its own if the Security Council balked.

Inspections were widely viewed as a way of delaying conflict, prompting Washington hard-liners to oppose them as a potential dead end.

Sooner than expected, however, Iraq appears to have challenged the Security Council with its suspect declaration, while giving the inspectors broad scope to follow intelligence leads and expose omissions and errors in the document.

"It's very hard to sustain a lie as broad" as Iraq's claim that it possesses no chemical or biological weapons and has no nuclear armaments program, a senior Bush administration official said this week. "Basically, every document, every individual and every site has to be lined up, or there is a vulnerability."

Privately, U.N. officials say the declaration mostly recycles previous disclosures that inspectors found inadequate.

The speed with which Iraq appears to have fallen afoul of the council's Nov. 8 resolution calling for complete disclosure and disarmament is surprising in light of the cooperation Iraqi officials have extended toward U.N. inspectors since they began work Nov. 22.

Many analysts had predicted that Iraq would embark on a strategy of at least partial cooperation in an effort to buy time and avoid giving the United States an excuse for launching a military attack during the winter months when conditions for U.S. troops would be optimal.

By disclosing a portion of its weapons programs, Iraq might have avoided an early confrontation with the Security Council and prolonged the U.N. inspections process. The Nov. 8 resolution required Iraq to make a "full, accurate and complete" declaration of all its nuclear, chemical and biological weapons programs.

Opportunity provided

Gary Samore, a senior fellow at London's International Institute for Strategic Studies, said, "I thought the Iraqis would declare some new information to make it difficult for the United States to argue that they were not meeting the requirements" of the resolution.

Instead, Hussein appears to have played into the hands of Washington hard-liners, and at the same time given them the opportunity to gain international support.

U.S. and U.N. officials caution that experts continue to pore over the 12,000-page Iraqi declaration and that it might contain more evidence than Iraq has suggested in its repeated public denials that it possesses weapons of mass destruction.

Mohammed ElBaradei, chief of the International Atomic Energy Agency, said yesterday that a 300-page section in Arabic contained "some new, additional information." But the bulk of the 2,700-page nuclear declaration was a repeat of Iraq's previous disclosures, he said.

Samore said Iraq might have feared that a partial disclosure "would quickly unravel and lead to exposure or release of [more] incriminating evidence," Samore said.

In a sign of assurance, the United States and Britain have decided to let Blix be the first to provide an extensive evaluation of the Iraqi declaration. The professional judgment of the U.N. inspectors will carry more weight with members of the council who suspect the United States is bent on finding a justification for war.

Even without access to intelligence that the Bush administration has kept under wraps, Blix has enough reason to suspect Iraq is hiding evidence to report that the declaration fails to pass muster, diplomats and officials said. Blix has said previously that Iraq must provide proof that it has disarmed. After he speaks, U.S. and British officials are expected to warn Iraq that it has moved closer to being found in "material breach."

Pressure on Iraq will mount, though gradually.

"I think the American and British game plan is to expose [flaws in] the declaration mainly by using the inspection process," Samore said.

Intelligence withheld

Although U.S. intelligence agencies have in recent weeks provided information to the inspectors to guide their search, they withheld "site-specific" intelligence that would direct inspectors to precise locations in large compounds.

As a result, inspectors have mostly visited previously known sites.

"Frankly, we don't have unlimited information, it's very sensitive, and we need to be sure they can use it in a timely way," a senior Bush administration official said in explaining why the Americans have been holding back intelligence. More intelligence will be provided as the inspectors get fully staffed, acquire more helicopters, equip on-the-ground laboratories and are able to use the information "swiftly and effectively," the official said.

On Thursday, Blix demanded in a letter that Iraq disclose all the names associated with its weapons programs. U.S. and U.N. officials are discussing ways to bring Iraqi scientists and their families outside the country for confidential interviews, although Blix has resisted American pressure to encourage defections.

ElBaradei of the IAEA told a news conference in Vienna yesterday that "if there is a need" to interview scientists outside Iraq, "we would not hesitate to use that authority."

The IAEA has been gearing up to take water samples that might indicate nuclear-weapons development.

While laying traps to expose Iraqi deception, the Bush administration is in no hurry to force a showdown. Weeks of diplomatic spadework are likely to be required before the United States lines up enough allies for a truly international war effort and persuades a reluctant Security Council to back it.

"The administration is going to take a little time here," said Republican Sen. Richard G. Lugar of Indiana, the incoming chairman of the Senate Foreign Relations Committee. After seeing the results of Washington's diplomatic efforts, he said, Hussein at the final moment "may change his mind" and agree to disarm.