We're coming to get you, Saddam (but it may take a little while)

George Bush has given Iraq six months' notice that he plans to invade, despite a lack of support from his allies. With a new doctrine that stretches the definition of self-defence, the United States may be sowing the seeds of worldwide anarchy, writes Rupert Cornwell

Has a war ever been so heavily signposted so long in advance, to the general indifference of so many? To all outward appearances, the US is on a glidepath to a military operation to get rid of Saddam Hussein at the end of this year or in the early months of next. It will be a war which few of America's allies want, of unpredictable consequences in a desperately unstable region. Yet in the US at least, everyone seems to consider it the most natural thing in the world.

The worries of others seem scarcely to impinge. Britain, which together with the US has been conducting a quiet bombing war against Iraq for the past four years, is probably the sole major ally America can count on – although Tony Blair will face far more vocal opposition at home than anything President Bush encounters.

US preparations for an attack continue in almost surreal disregard of what is happening elsewhere in the Middle East. The connection between Arab fury over Israel's treatment of the Palestinians and Arab reluctance to back the attack on one of their fellows is ignored; so too is the likelihood that an unprovoked attack on a Muslim country will merely fuel the existing resentment of America within parts of the Islamic world.

From the tone of its pronouncements you would think Washington was patting anxious allies on the head like parents taking a little child to the dentist for the first time: "Don't worry, we know what's good for you; it won't really hurt and when it's over you'll feel much better."

Any opposition voiced by governments in the Middle East is discounted, although the private message is different, assure those now familiar, ever anonymous "senior officials". Dick Cheney toured the region in March, and Paul Wolfowitz, the Deputy Secretary of Defense, was in Turkey last week trying to secure backing from a country whose air bases may be crucial for an invasion.

Back home, the polls say, most Americans buy the President's line: that unless this founder member of the "axis of evil" is halted in its tracks, Iraq will continue to develop nuclear, biological and chemical weapons, and either use them against the US or give them to terrorists who will do so.

There is no real public discussion – though finally the influential Senate foreign relations committee has announced it will hold hearings before the summer Congressional recess. Instead there are leaks. Almost every week brings more of them. Some suggest a massive air and land assault involving 250,000 or more troops; others point to an "Afghan" campaign, relying on aerial bombardment, special forces infiltration and help from Iraq's internal opposition (for Northern Alliance read the Kurds and the southern Shi-ites), or a combination of all the above.

According to one leak, the US intends to use Jordanian air bases in the assault (even though this proved to be news to Jordan, which opposes a war as strongly as any Arab country); then last week it was revealed that the Pentagon was perfecting a new type of bomb for use on suspected weapons plants, that would detonate not explosives but a thick coagulant or foam to prevent deadly chemical and biological agents being released into the atmosphere.

The overall message, though, is unmistakable: that planning for Gulf War II, of which the administration was talking even before 11 September, is now at an advanced stage. Mr Bush insists no final decision has been taken, but he has been briefed extensively by Tommy Franks, head of Central Command, who would be in charge of a new Iraq war.

The leaks bear every imprint of being deliberate sabre-rattling designed to unnerve Saddam, or provoke him into a move against the Kurds, say, which the US could use as a pretext.

But what if Saddam does not behave as the US intends? After all the tough talk from the White House, the sabre will have to be unsheathed anyway, in the interests of Mr Bush's credibility.

Iraq was the obvious target when the President went to West Point military academy to proclaim his alarming new doctrine of "pre-emptive response". In essence, America is now claiming the right to attack before it is attacked – a concept extending far beyond the right of self-defence enshrined in Article 51 of the United Nations charter, and amounting to carte blanche for Washington to intervene as and when it chooses.

But if the US can do that, why cannot any other country with a score to settle? A number of states used the American war on terror as an excuse to act aggressively against old rivals last year. "Pre-emptive response" could easily be a recipe for anarchy.

In any case, who is going to stop the US? This is a very different war from Gulf War I a decade ago, when the elder Bush sent 500,000 troops to the region to secure a return to the status quo, by liberating Kuwait and putting Saddam "back in his box". The aim of Gulf War II would be far more radical: "regime change" – even though Washington has no idea of the succession.

The truth is that whatever the objections in the Middle East or beyond, Washington seems not to care. Its military might, compared to both friend and foe, is even greater than in 1991. "Smart" weapons are far smarter now. A couple of US carrier groups carry more firepower than any country in the region. Allies in Europe and elsewhere may complain, but ultimately they are as mesmerised by US power as PGA golfers are by Tiger Woods.

Even the build-up may be quicker than expected. After Gulf War I, Washington left up to 35,000 men and much hardware in the region to deter Saddam from any more adventures. Anticipating a Saudi refusal to allow the use of its bases for a new attack, the Pentagon has begun shifting theatre command-and-control facilities to Qatar. Kuwait, already rescued once, can hardly deny the US whatever it wants now.

And what if Saddam is overthrown? No one knows what sort of regime might follow. The Iraqi opposition in exile is splintered and has little internal credibility. A permanent American presence might be needed to prevent the country from splitting – the very fear that kept Bush the father from going all the way to Baghdad.

Under the son, the mood is very different. Since 11 September, the concept of America as a "New Jerusalem" with its age-old sense of manifest destiny has been merging with America as a militarily irresistible "New Rome". Put more simply, America believes it is right, and is in no mood to let anyone stop it. Saddam and those folks in Baghdad better watch out.