The Bush administration is in the midst of making momentous decisions about how to deal with the United Nations in the post-Saddam era. Those decisions will critically affect our chances of winning the peace in Iraq and of proving our claims that Saddam had an arsenal of banned weapons-claims on which President Bush has staked his credibility. And they will set the direction of America’s relations with the rest of the world for years to come.

Many conservative hawks inside and outside the administration stress that the U.N. has been useless much of the time, as in Kosovo, and worse than useless some of the time, as in Srebrenica, Bosnia, where some 7,000 Bosnian Muslims were murdered in July 1995 while U.N. "peacekeepers" idled nearby. France and Russia are seeking to keep the U.N. embargo of Iraq alive as leverage "to get some Iraqi affirmation of their odious debts and oil contracts from the Saddam era," editorializes The Wall Street Journal. And with Libya’s repressive, blood-soaked government chairing its Commission on Human Rights and Saddam’s Iraq recently in line to head its May-June Disarmament Conference, the U.N. is often downright grotesque.

From such reasonable premises some U.N. critics draw a dangerous conclusion: that, in the words of columnist Charles Krauthammer, the United States should "just ignore" the U.N., should keep it out of Iraq, and should let it "wither away." The administration has not said that, but has taken an unwisely uncompromising approach, at least in its efforts to freeze Hans Blix and his team of U.N. inspectors out of the so-far-strikingly-fruitless hunt for banned weapons in Iraq. The exclusion of these independent inspectors is widely seen around the globe, especially in the Arab world, as designed to facilitate the planting of chemical or biological agents or other phony evidence. While administration officials dismiss such suspicions as preposterous, much of the world does not.

The Bush approach strikes Anne-Marie Slaughter, dean of Princeton’s Woodrow Wilson School, as "needlessly antagonistic and horrifically short-sighted in terms of our own objectives." I agree. Adds Slaughter in an interview, "We have created a situation in which it is so politically popular to oppose us that we are generating new adversaries for ourselves. If we were willing to work through the U.N., we could accomplish all the same objectives with virtually all the same people but with a completely different profile-in terms of [showing that] it’s not about oil, it’s not about U.S. imperialism, it’s not about Israel, it’s a global effort to find weapons of mass destruction and provide for the humanitarian needs of the Iraqi people."

For all of the U.N.’s grotesqueries, the hard reality is that its imprimatur is seen by many millions of people all over the world as essential to legitimate American actions that those people would otherwise oppose, and have opposed. U.N. approval was critical to winning support both for the post-9/11 war in Afghanistan, where Bush was glad to let the U.N. take most of the responsibility for nation-building, and for the first Gulf War, in 1991. We did not need the U.N. in order to win the war in Iraq. But we need all the help we can get to win the peace.

This does not mean that the United States should yield its hard-earned right to "significant dominating control" (in Colin Powell’s words) of Iraq’s political and economic reconstruction until such time as the U.S. is good and ready to do so-which, some officials have suggested, may be only a matter of months away. And it is not to suggest that we let Hans Blix take over the hunt for banned weapons.

But unless Bush seeks reasonable compromises with Blix and the U.N., he will aggravate distrust of America abroad to the point of harming our national security. For example, the already-widespread suspicions that the real motive for invading was commercial advantage will solidify unless we help put Iraq’s oil wealth under some kind of international trusteeship until Iraq has a working government and allow foreign companies to compete for contracts.

The U.N.-Blix imprimatur is especially critical to showing the world that Bush and his top people were honest when they vowed that their primary reason for invading was that they knew Saddam was amassing an arsenal of chemical and biological agents. I believed them then and still do (although I’m getting nervous). But if the world ends up doubting Bush’s truthfulness on a matter of such towering importance, it will be an utter disaster for America’s international standing.

We do not need Blix to find the evidence. But we do need independent verification, which Blix is best qualified to provide. Even if American investigators find tons of nerve gas, anthrax, or other smoking guns hidden outside Baghdad, much of mankind will suspect that they were planted unless Blix vouches for our claims. And Blix will be a lot more likely to do that if he and his inspectors are invited to move freely around Iraq, to do their own independent searches and find their own witnesses, and to accompany American investigators when they search new sites.

But the administration sees no role for Blix or his team "for the time being or for the foreseeable future," John D. Negroponte, the U.S. ambassador to the U.N., said on April 23. This at a time when the U.S. seeks resumed inspections by the U.N.’s International Atomic Energy Agency of North Korea’s nuclear facilities.

As a reporter asked White House spokesman Ari Fleischer, "What is the downside of having a hundred or so [U.N.] people in Iraq looking for weapons of mass destruction? Isn’t that more eyes on the problem?"

Fleischer did not have much of an answer. A candid response might go something like this: "We want complete control because we always want complete control, and because with it we can secure all the banned weapons and prove our claims that Saddam had them. Blix might slow us down or get in the way of our efforts to pressure Iraqi scientists to disclose what they know. His inspectors might-intentionally or otherwise-tip off hostile intelligence agencies or Iraqis about where we plan to look. They might endanger confidential informants by leaking their identities. Besides, Blix was unhelpful before the war and now accuses us of having presented the U.N. with shaky intelligence. If we let him in, he might cast doubt on the veracity of our informants or investigators."

But the notion that cooperating with Blix would or could substantially impede our own search for banned weapons seems fanciful. What is he going to do-run around Iraq scooping up and hiding tons of artillery shells loaded with nerve agents, anthrax, and uranium-enriching gas centrifuges?

Blix could not possibly do that even if he tried. After all, there are supposed to be lots of banned weapons scattered around Iraq. There are many more American investigators than there would be U.N. inspectors. Blix could not restrict the Americans’ movements. A standing invitation for Blix’s people to accompany American investigators whenever they search for banned weapons could be accompanied by a warning that they will be left behind if they move too slowly. And the U.S. could work out reasonable restrictions on U.N. inspectors’ access to any U.S. informants who want anonymity.

What if we never find much because the smoking guns were destroyed or moved to Syria before the invasion, as U.S. investigators have been told by an Iraqi informant, according to Judith Miller of The New York Times? That scenario strains credulity at best. How could Saddam have gotten rid of vast quantities of banned weapons in such a hurry while preparing to be invaded? What would have motivated him to go to such lengths to prevent American occupiers from finding smoking guns after his death or removal? And who would believe us if the Iraqi witnesses on whom we rely were kept away from Blix and completely dependent on and controlled by the U.S. and Britain?

The goal here is to find evidence that will be believed. And the policy of excluding Blix seems almost perversely calculated to inspire disbelief. Indeed, it seems so self-defeating as to suggest either a disturbing lack of confidence that Saddam had very many banned weapons, a petty vindictiveness, or a mindless determination to compromise on nothing until France and Russia agree to end the embargo. I prefer the latter theory. In any event, such a gratuitously hostile posture toward the U.N. will, if continued, make it more and more difficult to keep the support even of our closest ally, Tony Blair’s Britain. And if we lose Tony Blair, we will be isolated indeed.