By this time next Sunday, Tony Blair will have finished discussing the attack on Iraq at President Bush's Texas ranch. Mr Blair and his advisers are not just resigned to having to go along with the US; there is genuine enthusiasm for taking action against a dictator whom the Prime Minister believes to be public enemy number one.
But these enthusiasms are confined to the inner circle at No 10. The Chief of Defence Staff, Sir Michael Boyce, has reflected the views of senior figures in the military establishment by suggesting that we should learn to live with weapons of mass destruction, and that if, as he put it, Britain was deliberately going to put its "hand in the mangle" of Afghanistan, we should not simultaneously do so in Iraq.
Scepticism about military expeditions to Iraq and the recent deployment of troops to Afghanistan has spread beyond the usual suspects. A retired wing commander rang me to express his fears about our troops operating under the command of the US army. His peacetime service under US air force generals had been bad enough, he said, and US army generals were of poorer quality.
This uncertainty means that Mr Blair has to take this opportunity to find out what military action Mr Bush really intends in his expanding war against terror.
Almost as important is the need to get an understanding of how the US decision-making process works. As one US intelligence official told me, only eight people in Washington are now allowed to read even quite low-level intelligence assessments, which for decades had been circulated to several dozen. Mr Bush's inner team already had a notoriously narrow worldview and are now preventing even their senior advisers from being properly briefed.
The broad strategy is very clear. For American Republican strategists, the desire to crush President Saddam Hussein is not really about revenge or weapons of mass destruction. It has far more to do with the need to show that it is not possible for any state or individual to fight the US and survive. For today's Republicans, "Make My Day" is a motto for the real world.
The plans being considered are intended to provoke an internal coup and a rebellion by the Kurdish and Shia minorities. The optimum scenario involves a massive air attack supporting a ground attack from three directions. An assault by 30,000 US troops already in Kuwait would be accompanied by the seizure of Iraqi airbases by the 82nd Airborne Division with, in the north, the assistance of the Turkish army.
Supporters of this view outside government include President Reagan's former arms control adviser Ken Adelman, who believes that the war would be over in a month. It could take place as early as this summer, be preceded by the production of evidence of Saddam's weapons programmes, and base its legitimacy under the UN on the argument that Saddam is in breach of the ceasefire agreement that ended the 1991 Gulf War. In this strategy, American troops would be hailed as liberators in Baghdad, and exiled Iraqi officers would form a new government.
Concerns over Iraq's use of chemical or biological weapons on Israel, the reaction in the Arab world, and lack of international support would be dismissed as inevitable in any circumstance and so, it is argued, we might as well get it over with. Mr Bush's natural decisiveness is supported by his National Security Adviser, Condoleezza Rice. She takes as a model the way she helped Mr Bush's father push through German unification in the face of objections from both Margaret Thatcher and François Mitterrand.
A slower build-up, leading to an assault by 300,000 troops around the end of the year may be more likely, as it would give a higher chance of military victory, but it runs the risk that Saddam or other international events will delay things still further. In this scenario a cat-and-mouse game over UN weapons inspections would be allowed to run on until after the US mid-term elections and until a massive force could be assembled. All the current sabre-rattling is simply designed to intimidate Saddam into compliance. But a game of triple bluff is also possible, in which Saddam is made to believe the current rhetoric is a bluff and then is attacked anyway.
It is unlikely that the decision has been made yet. For from behind closed doors can be heard the muffled sounds of an epic Washington dogfight among Mr Bush and his advisers. Public support for the President as well as the collapse of the Taliban have concealed incompetence and mismanagement of the war against terror. A senior defence official in London recently told me that he considered the "axis of evil" speech as little more than the justification for spending billions on hi-tech weapons favoured by the US Defense Secretary, Donald Rumsfeld, but largely irrelevant to the war on terrorism. Meanwhile, Mr Bush has left the coastguard underfunded. There is also no cash to produce a uniform system for turning Arabic words into English, so someone being observed by different agencies can elude detection simply by having his name written differently in English by the people trying to catch him.
US inter-service rivalries have also got in the way of the effective conduct of the war. At first the US Air Force insisted on using B-2 and B-1 bombers as well as the veteran B-52s, in order to justify their vast cost, but their defects soon proved too obvious and the US fell back on the old and reliable B-52s.
In recent weeks the ill-fated attack by the US army at Gardez was the product of the desperate attempt by the army to get in on the action, previously dominated by the US Marines. Up to Tora Bora all the glory had gone to the USAF's carrier-based "top guns", special forces and the marines. Fearing that it would lose out in the defence budget, army chiefs pushed for a mission. The result was a laboriously planned attack by troops of the 10th Mountain and 101st Airborne Divisions, which was comprehensively ambushed by the guerrillas. The ensuing row resulted in the urgent request for British help, one of our major assets being that we are not part of the inter-service rivalries.
Communication has virtually broken down between the US's top commanders. General Franks refuses to talk to or visit the Pentagon even to give press briefings. In a deliberate power play, Donald Rumsfeld walked out of a top White House meeting called by Ms Rice on options for attacking Iraq after just five minutes, saying he was too busy to stay. Such is his influence that colleagues fear that he may simply stop by the White House one evening and get Mr Bush to sign the attack order on Iraq.
His decisiveness might be reassuring. But both he and the chairman of the Joint Chiefs of Staff, Richard Myers, seem dangerously ignorant of critical details. At the press conference following the killing of eight US soldiers in Afghanistan, neither was able to talk about the poor performance of helicopters at high altitude where their rotor blades struggle to get a grip on the thin air. Behind a cloak of public silence there is much ego-driven headbutting and a very narrow sense of what is important. Such is the closed circle of US policy-making that whatever Tony Blair learns at the Crawford Ranch will be more valuable than anything that MI6 could produce.
I recall the honest query of one of Mr Rumsfeld's aides: "Why are we getting all this support from Blair? Thatcher we could understand, but we know he's not one of us." Why indeed? Mr Blair needs to return from the depths of Texas with an answer to convince his own party, his military top brass and the British people. If he does not, much more than just his premiership will be at stake.
Dan Plesch is author of '"Sheriff and Outlaws in the Global Village' (Menard Press) and senior research fellow at the Royal United Services InstituteReuse content