When President Bush addresses the UN General Assembly Thursday, pressing his case against Iraqi leader Saddam Hussein, he will be asking the world to alter the founding principles of the post-World War II international order.
Advocating preemptive military action against Baghdad before it uses its alleged chemical, biological, or nuclear weapons, Mr. Bush is challenging United Nations rules on sovereignty and the acceptable use of force that have underpinned global relations for three generations.
To the Bush administration, this is a matter of adapting to a new danger. But this argument will likely alarm the vast majority of UN members listening to the US leader. They know that their best chance of restraining Bush is to meet him partway, by threatening to use force on their own terms against Iraq if Mr. Hussein does not cooperate with UN weapons inspectors as suggested this week by French President Jacques Chirac.
Bush faces a difficult task in bridging the gap that currently separates him from almost every other world leader over how to deal with the Iraqi government.
Washington has openly set "regime change" as its goal, claiming that Mr. Hussein is amassing weapons of mass destruction for use against America and its allies and that he must be deposed before he gets a chance to use them.
"Time is not on America's side," presidential spokesman Ari Fleischer warned recently.
The closest that any US ally has come to supporting Bush's position is British Prime Minister Tony Blair's warning Tuesday that "action will follow" if Iraq ignores demands to allow arms inspectors back into the country.
Most European governments are expected to back the sort of proposal that French President Jacques Chirac made earlier this week, for a two-stage UN procedure. Under a first resolution Iraq would be given three weeks to allow inspectors in without conditions, and if it refused, a second Security Council resolution would be passed on whether or not to use military force.
It is not clear, however, that such a plan will satisfy Washington, where officials are afraid that Hussein might accept inspectors but then prevaricate and withhold cooperation, rendering their work of dubious value.
Bush has been working hard to win international support for a military strike against Iraq. He has telephoned or met with many world leaders in recent days, starting with the rulers of Washington's partners on the UN Security Council, Russia, China, Britain, and France. And his speech Thursday to the UN is expected to be a keystone of his campaign to explain US fears and intentions.
But the administration seems increasingly ready to act alone against Baghdad if it cannot convince the rest of the world that Iraq poses a clear and present danger to its neighbors and to others.
Militarily, the US could certainly do so. But unilateral action could cause a diplomatic earthquake that would topple several pillars holding up the edifice of international stability.
By attacking Iraq without UN endorsement, Washington would be arrogating to itself the right to decide what constitutes a threat to world peace, and what to do about it. That would be a significant break from international norms.
As UN Secretary-General Kofi Annan underscored Wednesday, only the UN Security Council could provide "the unique legitimacy that one needs to be able to act" against threats to international peace.
If the US goes it alone, that "neo-imperial vision," argues Georgetown professor John Ikenberry in the current edition of Foreign Affairs magazine, "could transform today's world order in a way that the end of the cold war ... did not."
Of course, the concept of national sovereignty has been changing since the end of the cold war, with governments and their agents less and less able to act with impunity: NATO justified as "humanitarian intervention" its bombing campaign against Serbia to force an end to repression in Kosovo, for example.
"Simply put, sovereignty does not grant governments a blank check to do whatever they like within their own borders," State Department director of policy planning Richard Haass argued recently. And since Sept. 11, he added, "countries affected by states that abet, support, or harbor international terrorists ... have the right to take action to protect their citizens."
The Bush administration has taken this concept used to justify the attack on Afghanistan a good deal further in recent months.
Deterrence and containment the doctrines used to keep the peace during the cold war are worthless against terrorists prepared to sacrifice themselves, the president argued last June at West Point.
"We must take the battle to the enemy, disrupt his plans, and confront the worst threats before they emerge," he said. "Our security will require all Americans to be forward-looking and resolute, to be ready for preemptive action when necessary to defend our liberty and to defend our lives."
Many US allies would agree with the strategic thinking behind this approach to a new terrorist threat, but they are fearful of international anarchy should the US act alone.
Nothing would keep other countries from deciding that a threat to their national security justified a preemptive armed strike, President Chirac said this week, citing India and Pakistan, or China in its dispute with Taiwan as possible examples.
In the case of Iraq, the world's worries were best summed up Monday by Canadian Deputy Prime Minister John Manley. "As for going in and changing the regime, as opposed to going in and ensuring that there are no weapons of mass destruction, we haven't signed on to that," he said.
US and British diplomats at the UN are preparing to draft a Security Council resolution possibly with French help demanding that Iraq cooperate with arms inspectors as it agreed to do under the terms of its surrender at the end of the Gulf War in 1991. Inspectors withdrew in 1998 on the eve of a US and British bombing campaign in Iraq, and have not been allowed back in since. But only in recent weeks has their four-year absence become a matter of serious international concern.