Why are we on the brink of attacking Iraq? One thing is certain. It's not to respond to domestic public opinion, which is almost universally hostile to such an idea.

I have had countless letters, emails, faxes and phone calls from constituents, all opposed to such an attack. And this time they come from retired bankers just as much as from "peacenik lefties".

We are told Saddam Hussein has weapons of mass destruction. I expect he has. After all, the US and UK sold him plenty when we wanted his support against Iran.

US Defence Secretary Donald Rumsfeld personally met him in 1984 on behalf of President Reagan to facilitate the sale of viruses such as anthrax and bubonic plague.

When Iraq used such weapons against its own people, what did the West do? Nothing.

Saddam Hussein is a deeply unpleasant man who clearly has no compunction about using any weapons he can get his hands on if he can get away with it. But that is the key point. Saddam has lasted a long time in power.

He is not stupid. Gassing the Kurds is one thing. He would be mad to attack the US or UK and so has never threatened to do so.

Yet now we are talking about launching an attack on him, with UN support if it can be garnered but without, it seems, if it cannot.

So Iraq has to stick by the letter of UN law, but the US and UK give themselves the right to start a war if the UN won't play ball, even if the weapons inspectors find nothing at all.

To launch such an attack is legally an act of war for which there is no defence in international law.

Then there are the other political risks. Where is the Iraqi opposition? Who would replace Saddam Hussein? An American general? And what would such an attack do for the Middle East peace process? It would in fact destabilise the region and confirm in Arab eyes there is one rule for Israel and one for the Arabs.

After all, Israel is in breach of more than twice as many UN resolutions as Iraq and is, unlike Iraq, a nuclear power. What is the US doing about that?

Then there is North Korea. If the US really wants to tackle rogue states, here is one virtually shouting from the rooftops. It has this week announced it is pulling out of the Nuclear Non-Proliferation Treaty. And what is the US response? Low-key dialogue.

So is it wild inconsistency? Or is there a more sinister explanation?

Let's go back to the terrible events of September 11, 2001. Since then, some rather odd facts have emerged. First, in the months before, the US received explicit warnings of such an attack from Russia's President Putin ("in the strongest possible terms"), Egypt, Israel, Jordan, Germany, from numerous individuals, even from its own FBI. Some of these were date and place specific. We know from CBS News these reports reached President Bush.

We also know that on that terrible day, although four planes were hijacked practically simultaneously. Air Force interceptors, contrary to established procedure, did not take to the air until 50 minutes after the North Tower had been struck. Why? Was it total incompetence? Or did someone powerful actually want a way to persuade public opinion the US should attack Afghanistan?

We also now know that in the years before, US interests had been negotiating with the Taliban to lay a pipeline across Afghanistan to get oil from Turkmenistan to Pakistan. They had refused.

We also know the US threatened to attack Afghanistan before September 11. So here is the connection between Afghanistan and Iraq. Not rogue states but oil. Something North Korea does not have. As former US National Security Adviser Zbigniew Brzezinski said in 1997: "who controls Caspian oil and gas controls the world".

Let us not forget Bush and Cheney have oil coursing through their veins. They have money in it. Then there is Condoleezza Rice, the National Security Adviser, who used to work for Chevron-Texaco. Or the Union Oil of California company, who wanted that pipeline across Afghanistan, and whose employee John Maresca is now the US envoy to the country, and whose former employee Hamid Karzai is now President.

Oil is running out fast, production is due to peak very shortly, yet consumption is still increasing, especially in the US which, by 2020, will be importing 90 per cent of its needs. The last major supplies are to be found in the Caspian, in Saudi Arabia, and in Iraq, the latter with 11 per cent of the world's total supplies.

I fear we are seeing a US-led strategy, involving sequential aggression if necessary, to get control of the oil that remains.

I hope I am wrong but I fear I am not. Either way, no case has been made that convinces the British people we should attack Iraq.

We cannot perhaps stop the Americans but we can stop ourselves.

Norman Baker is the Liberal Democrat MP for Lewes