The U.N. Security Council unanimously approved a tough new disarmament mandate for Iraq today, warning President Saddam Hussein he must scrap his weapons programs or face "serious consequences" that almost certainly would be a U.S.-led war against his government.

The 15 to 0 vote represented a significant achievement for the Bush administration. It has spent nearly eight weeks working to satisfy the demands of Russia, France and other nations that the United States pursue its Iraq policy under U.N. auspices, even as it refused to abandon its ultimate goal of confronting Hussein -- through force if necessary.

The resolution was endorsed not only by Russia and France but also by Syria, a council member that until the final minutes had said it would oppose the measure directed against its neighbor and fellow Arab state. Syria's deputy U.N. representative said his government agreed to support the resolution only after receiving "high level" assurances from Washington, London, Paris and Moscow "that this resolution would not be used as a pretext to strike Iraq."

Speaking in the Rose Garden minutes after the vote, President Bush renewed his warning -- set out in his Sept. 12 speech to the U.N. General Assembly -- that Iraq must dismantle chemical, biological and nuclear weapons programs or face the prospect of war.

"With the resolution just passed, the United Nations Security Council has met important responsibilities, upheld its principles and given clear and fair notice that Saddam Hussein must fully disclose and destroy his weapons of mass destruction," Bush said. "His cooperation must be prompt and unconditional or he will face the severest consequences."

The adoption of Resolution 1441 set the stage for the return of an advance team of U.N. weapons inspectors to Baghdad on Nov. 18, resuming a disarmament process that ended in late 1998 when inspectors withdrew shortly before the United States and Britain launched airstrikes against Iraq to protest Hussein's intransigence.

Armed with a strong new mandate and backed by a unified council, the inspectors face a challenge of squeezing a complicated and ambitious disarmament effort into a tight schedule. They must report back to the United Nations on Iraq's hidden weapons program within just over three months.

The rare display of unity in the council will increase pressure on Hussein to grant the inspectors unprecedented access to suspected weapons facilities.

"I urge the Iraqi leadership -- for the sake of its own people, and for the sake of world security and world order -- to seize this opportunity, and thereby begin to end the isolation and suffering of the Iraqi people," U.N. Secretary General Kofi Annan said after the vote. "If Iraq's defiance continues, however, the Security Council must face its responsibility."

Iraq's U.N. ambassador, Mohammed Douri, said his government would study the resolution and decide "whether we can accept it or not." But he told Reuters that he is "very pessimistic."

"This resolution is crafted in such a way to prevent inspectors to return to Iraq," Douri said.

There was no official reaction in Baghdad. A commentary read on an Iraqi satellite television channel said "the resolution represents the dream" of U.S. policies, "which have pushed the world to the edge of war and violated for 12 years international laws and norms."

Bush's closest foreign ally, British Prime Minister Tony Blair, repeated the president's threat, warning Hussein that he will face military action if he violates the terms of the resolution.

"Defy the U.N.'s will and we will disarm you by force," Blair said outside 10 Downing Street, his official residence, shortly after the vote.

Although the resolution falls short of the automatic endorsement of military force that the United States initially sought, U.S. officials maintained that it preserves the president's authority to strike Iraq if the United Nations fails to disarm it. The final deal on the text was struck only after the administration provided assurances that it would give the council a chance to consider any Iraqi violations before undertaking military action.

"One way or another . . . Iraq will be disarmed," John D. Negroponte, the U.S. ambassador to the United Nations, said after the vote. "This resolution doesn't constrain any member state from acting to defend itself against the threat posed by Iraq."

Senior U.S. officials said the resolution preserved the three main elements sought by Bush. It finds Iraq in "material breach" of its disarmament requirements, defines Iraq's obligations and threatens "serious consequences" if it fails to comply -- a phrase the administration interprets as an endorsement of military action. Other council members differ.

France, Russia and other countries that oppose U.S. military action said the resolution diminishes the likelihood of war and establishes a pivotal role for the Security Council in deciding what kind of response Iraq will face if it flouts the resolution.

"The resolution deflects the direct threat of war," Russia's U.N. ambassador, Sergey Lavrov, told the council. "As a result of intensive negotiations, the resolution that has just been adopted does not contain any provision about automatic use of force."

Jean-David Levitte, France's U.N. ambassador, said the resolution "strengthens the role and authority of the Security Council," in determining whether Iraq will face military action. But he made it clear that even the council's patience is limited.

"War can only be a last resort," Levitte told the council. "The rules of the game set by the Security Council are clear and demanding. If Iraq wishes to avoid confrontation, it must understand that the opportunity it has been given is the last."

The unanimous adoption of the resolution represented a personal victory for Secretary of State Colin L. Powell, who had advised Bush to pursue Iraq's disarmament through the United Nations.

Powell was convinced as early as Oct. 30 that he had secured the nine votes required for adoption of the resolution. But he decided to press ahead in the hope of unifying the council behind Washington's policy -- a course whose outcome was not determined until just before the 15 Security Council members sat down to vote.

France had led efforts to water down the resolution, but embraced the measure after a telephone conversation Thursday between Bush and French President Jacques Chirac. Powell followed with a phone call to French Foreign Minister Dominique de Villepin and worked out a final compromise that strengthens the role of inspectors in determining Iraqi violations.

Bush was unable, however, to extract a commitment from Russia President Vladimir Putin to follow suit. But Russian Foreign Minister Igor Ivanov phoned Powell at 9 o'clock this morning -- an hour before the scheduled vote -- and "said they would be voting yes," a senior U.S. official said.

That left Syria. "We were still not sure about the Syrian vote," the official added.

On Thursday night, Syria's deputy U.N. representative, Fayssal Mekdad, told the council it might be "impossible" to vote for the resolution. But under intense pressure from the United States, France and Britain, he informed Negroponte minutes before the vote he would back the resolution.

After eight weeks of often difficult negotiations, the vote was over in an instant. Chinese Ambassador Zhang Yishan, the council's current chairman, sat down in the buzzing chamber, called the meeting to order and asked for a show of hands.

Fifteen rose around the table -- those of the permanent five (the United States, Britain, Russia, France and China), as well as Syria, Colombia, Ireland, Mauritius, Norway, Singapore, Bulgaria, Cameroon, Guinea and Mexico.

The resolution reinforces U.N. inspectors' rules of engagement in Iraq. It provides them with the authority to demand "immediate, unimpeded, unconditional, and unrestricted access" to any site, including eight presidential compounds that have been subject to special procedures that rendered surprise inspections impossible.

Iraq is required to confirm within seven days that it intends to comply. It has an additional 23 days to provide a "currently accurate, full and complete declaration" of the status of its civilian and military biological, chemical and nuclear programs.

The inspectors will have up to 45 days to begin their inspections, and 60 additional days to report to the council. However, Hans Blix, the chairman of the U.N. Monitoring, Verification and Inspection Commission, said he can report a violation to the council at any stage of the inspections.

Blix and Mohammed El Baradei, the director general of the International Atomic Energy Agency, will lead an advance group of U.N. inspectors to Iraq on Nov. 18. A team of about 12 inspectors will arrive a week later to begin the first inspections. U.N. officials said they would build up a team of 80 to 100 inspectors over the following weeks.

The resolution adopted today declares Iraq in "material breach" -- a term previously invoked to justify military action against Baghdad -- of its disarmament obligations. It warns Iraq that it has one "final opportunity" to scrap its deadliest weapons. And it threatens to consider undefined "serious consequences" if Baghdad continues to defy weapons inspectors.

Correspondent Rajiv Chandrasekaran in Cairo contributed to this report.

Fayssal Mekdad, left, of Syria, Jeremy Greenstock of Britain and John D. Negroponte of the United States raise their hands in support of the Security Council's resolution ordering Iraq to comply with U.N. weapons inspections. The resolution passed by a 15 to 0 vote.British U.N. Ambassador Jeremy Greenstock, left, and U.S. Ambassador John D. Negroponte shake hands after voting on Iraq resolution.Secretary of State Colin L. Powell, President Bush confer at White House. Bush said the Security Council "has met important responsibilities."