I want to debate entirely in terms of British interests the rights and wrongs of going to war with Iraq. Yes, I mean a wholly selfish appraisal of the advantages and disadvantages of our troops, our aircraft and naval units, our tanks, and our money being used in this enterprise. For these purposes, I don't wish even a shred of morality or sentimentality to enter into the argument; let us concentrate solely on what suits or does not the inhabitants of these islands.

I want to debate entirely in terms of British interests the rights and wrongs of going to war with Iraq. Yes, I mean a wholly selfish appraisal of the advantages and disadvantages of our troops, our aircraft and naval units, our tanks, and our money being used in this enterprise. For these purposes, I don't wish even a shred of morality or sentimentality to enter into the argument; let us concentrate solely on what suits or does not the inhabitants of these islands.

The primary reason for launching an attack on another country is self-defence. British defence chiefs feel this strongly: for it to be right to attack, aggression has to be present from the opposite direction. What, precisely, would we be defending ourselves against? As we are not expecting military attack on the United Kingdom or its possessions, what other forms of aggression would we be countering?

Two possibilities are apparent. The first is that, if unchecked, Iraq would again invade one of its neighbours and this would be against our interests. Given the earlier attacks on Iran and Kuwait, this must be considered likely. But I have changed my mind about the significance of this scenario. I supported the first Gulf War to liberate Kuwait, but I now think that I was wrong to do so.

The border between the two countries was arbitrarily placed there by the British 80 years ago. The conflict was a purely regional one, far from our shores. Its outcome had no implications, either favourable or unfavourable for us. Neither government had any democratic legitimacy. Oil would be pumped anyway because the Middle East has no other major source of revenue. In fact, the Western involvement in the conflict led to oil-extraction facilities being destroyed and a toxic fire storm. It was therefore counter-productive in the short term. And Kuwait still has the same type of government.

I don't believe that we have received any lasting value from the loss of lives and the expenditure of considerable resources, nor would we do so in the similar circumstances in the future.

The second possibility under the heading of other forms of aggression is that Saddam Hussein is financing terrorist groups; supplying them and training them with the objective of carrying out attacks in this country, as well as in others. Whether they belonged to the al-Qa'ida network or not would scarcely matter. This is a plausible threat that must be considered. Unfortunately, the Government's assertions on this subject are worthless because they are largely tendentious and inaccurate.

People have to rely on their common sense, on leaked intelligence assessments and on the work of media correspondents in the field. And common sense alone tells us that, even if Iraq were rendered incapable of sponsoring terrorist attacks on the West, other groups and other countries hostile to the hawkish British and Americans would thereby redouble their efforts. In practice, I believe an allied attack on Iraq would increase the risk of terrorist activity within Britain rather than diminish it.

After considerations of self-defence comes the second-order issue of international security. The creation of an international framework of law governing the behaviour of nations would be a great blessing. It is undoubtedly in our interests that United Nations resolutions are enforced – provided that such action does not compromise our ability to defend ourselves. That is why I call it a second-order consideration.

However, Saddam has flouted 116 UN resolutions in 12 years. He has violated the resolutions which ended the first Gulf War. He is likely to be in breach of resolution 1441 which demands that he gives up all weapons of mass destruction. Hence the Prime Minister's repeated message that, if we show weakness now, no one will believe us in the future. Likewise, David Owen states: "This war, if it comes, will be about asserting the authority of the UN Charter."

To which it can be added that this war, if it comes, will be because the United States and Britain, at least, have lost faith in the current policy of containing Iraq as a response to Saddam's defiance. Undoubtedly, containment has many disadvantages. Despite over-flights by American and British warplanes, despite substantially reduced oil revenues, despite periodic visits by UN inspectors, it allows Saddam – albeit with great difficulty – to work at acquiring weapons of mass destruction. At the same time, containment inflicts great suffering on Iraqi citizens by depriving them of medical facilities.

This is a genuinely difficult choice. Containment to enforce the UN resolutions on the one hand, which is what France and Germany continue to argue for, or invasion as an act of liberation which America and Britain support. Both policies cost lives, only the timing differs. The second also, as I have noted, increases the possibility of terrorist attacks within Britain. Furthermore, it represents American revenge for 11 September, which is not our business, and it demands from the US a commitment which it has repeatedly walked away from since General Douglas MacArthur left Japan in the early 1950s: nation-building.

Taking account of all these factors, I believe that a prudent reading of British interests would favour a continuation of containment, not war.