Washington ? Saddam Hussein is many things: Vicious murderer, genocidal dictator and mustachioed popinjay come to mind immediately. Madman, fool and quitter do not. The small band of United Nations weapons inspectors who resumed work in Iraq this week after a four-year absence will have a tough time nailing the master survivalist.

But the U.N. hunt for weapons of mass destruction is only one of three variables that will now determine whether there will be war or peace in Mesopotamia this winter. The much-heralded inspections in fact rank far behind the two other triggers for war: Saddam’s behavior, and the resolve of George W. Bush and Tony Blair to end the Iraqi leader’s tyranny.

The most likely result of these imperfect, limited inspections is ambiguity. If the inspectors cannot find a smoking poison-gas canister in Saddam’s hands, neither are they going to be able to clear him of the charges that Bush has already brought. Bush will have to decide on the basis of imperfect evidence whether Iraq really poses the urgent and massive threat the president has spent a year describing.

The Iraqis have rigged the inspection game for more than a decade. They have had four unfettered years to perfect their concealment operation. They will quickly find ways to penetrate the U.N. team ” if they have not already done so. Even a good-faith, all-out effort by the inspectors, which is far from guaranteed, faces enormous obstacles.

That is why the most surprising outcome for me would be for Bush to accept long, drawn-out and predictably inconclusive inspections that essentially leave the Iraqis in control of timing and process. This president’s words, his temperament and his interests rule out that waiting game.

By going to the U.N., Bush has not surrendered the timing or the substance of his military options. He is in a better position today to demand support from the American public, his foreign allies and the United Nations than he was last summer, before he decided to give multilateralism a last chance to disarm Iraq.

The political and diplomatic costs of going to war dominate public discussion. But imagine the costs involved in the opposite situation of an American president failing to deal with a serious threat to world peace because he has been boxed in by U.N. inspections that are seen to be ineffective or rigged.

That result would shatter Bush’s presidency, beginning with his national security team, which argued bitterly over the inspections last summer. It would erase significant U.S. support for the United Nations for a decade and more. America’s influence in the Middle East and its protective shield for Israel would be shredded.

The most serious arguments within the administration “were over what kind of inspections there should be,” says one U.S. policy-maker. “The inspections have to test quickly whether there has been a strategic shift in Iraq on weapons of mass destruction. If there has not been, there is no point of going through elaborate procedures that are unlikely to turn up much new.”

The administration has targeted the full and truthful inventory of banned weapons that Iraq is required to make by Dec. 8 as the first litmus test of Saddam’s intentions. U.S. officials have also pressed Hans Blix, who heads the inspection operation, to launch early and effective probes of Iraq’s “concealment mechanisms” ” the special units and mechanisms that protect Saddam’s store of horror weapons and his hiding places.

“Blix didn’t promise much,” said one disappointed U.S. official. “But if you believe Saddam is a control freak who will not tolerate any serious inspection effort, it may not take much.”

British Prime Minister Blair is said to believe just that: War is inevitable because Saddam cannot tolerate challenges to absolute political control inside Iraq. Blair constantly pushed Bush to accept softer terms for the new Security Council inspection resolution, apparently arguing that, in the end, the inspection results would be less decisive than the challenge they pose to Saddam. In any event, Britain would be with the United States in any military operation.

The Bush administration asserts that enormous positive change will flow across the Middle East from a successful disarming of Iraq. Failure will increase and entrench the dangers that Americans face from a sworn enemy.

Having identified and articulated those enormous stakes, can Bush and Blair leave the decision about Iraq’s fate solely in the hands of Hans Blix, a studious, by-the-book Swedish treaty lawyer who failed to detect Saddam’s nuclear program the first time around? Did George W. Bush become president to have that happen? The prospect boggles the mind and chills the blood.

Jim Hoagland is a columnist for Washington Post Writers Group.