Public interest in the forthcoming appearance of Tony Blair before the Chilcot panel is already high and the ballot for tickets to the occasion takes place today. Yesterday the Sunday Times published a document that has raised anticipation for the occasion even higher: a leaked 2002 letter to Blair from Jack Straw, in which the then foreign secretary expresses his strong doubts about the wisdom of invading Iraq. This is the text of that letter, dated 25 March 2002.

SECRET AND PERSONAL PM/02/019

PRIME MINISTER

Crawford/Iraq

1. The rewards from your visit to Crawford will be few. The risks are high, both for you and for the government. I judge that there is at present no majority inside the PLP for any military action against Iraq, (alongside a greater readiness in the PLP to surface their concerns). Colleagues know that Saddam and the Iraqi regime are bad. Making that case is easy. But we have a long way to go to convince them as to:

(a) the scale of the threat from Iraq and why this has got worse recently;

(b) what distinguishes the Iraqi threat from that of eg Iran and North Korea so as to justify military action;

(c) the justification for any military action in terms of international law; and

(d) whether the consequence of military action really would be a compliant, law-abiding replacement government.

2. The whole exercise is made much more difficult to handle as long as conflict between Israel and the Palestinians is so acute.

The scale of the threat

3. The Iraqi regime plainly poses a most serious threat to its neighbours, and therefore to international security. However, in the documents so far presented it has been hard to glean whether the threat from Iraq is so significantly differently from that of Iran and North Korea as to justify military action (see below).

What is worse now?

4. If 11 September had not happened, it is doubtful that the US would now be considering military action against Iraq. In addition, there has been no credible evidence to link Iraq with UBL and al-Qaida. Objectively, the threat from Iraq has not worsened as a result of 11 September. What has however changed is the tolerance of the international community (especially that of the US), the world having witnessed on September 11 just what determined evil people can these days perpetuate.

The difference between Iraq, Iran and North Korea

5. By linking these countries together in this "axis of evil" speech, President Bush implied an identity between them not only in terms of their threat, but also in terms of the action necessary to deal with the threat. A lot of work will now need to be to de-link the three, and to show why military action against Iraq is so much more justified than against Iran and North Korea. The heart of this case – that Iraq poses a unique and present danger – rests on the facts that it:

• invaded a neighbour;

• has used WMD and would use them again;

• is in breach of nine UNSCRs.

The position in international law

6. That Iraq is in flagrant breach of international legal obligations imposed on it by the UNSC provides us with the core of a strategy, and one which is based on international law. Indeed, if the argument is to be won, the whole case against Iraq and in favour (if necessary) of military action, needs to be narrated with reference to the international rule of law.

7. We also have better to sequence the explanation of what we are doing and why. Specifically, we need to concentrate in the early stages on:

• making operational the sanctions regime foreshadowed by UNSCR 1382;

• demanding the readmission of weapons inspectors, but this time to operate in a free and unfettered way (a similar formula to that which Cheney used at your joint press conference, as I recall).

8. I know there are those who say that an attack on Iraq would be justified whether or not weapons inspectors were readmitted. But I believe that a demand for the unfettered readmission of weapons inspectors in essential, in terms of public explanation, and in terms of legal sanction for any subsequent military action.

9. Legally there are two potential elephant traps: (i) regime change per se is no justification for military action; it could form part of the method of any strategy, but not a goal. Of course, we may want credibly to assert that regime change is an essential part of the strategy by which we have to achieve our ends – that of the elimination of Iraq's WMD capacity; but the latter has to be the goal; (ii) on whether any military action would require a fresh UNSC mandate (Desert Fox did not). The US are likely to oppose any idea of a fresh mandate. On the other side, the weight of legal advice here is that a fresh mandate may well be required. There is no doubt that a new UNSCR would transform the climate in the PLP. Whilst that (a new mandate) is very unlikely, given the US's position, a draft resolution against military action with 13 in favour (or handsitting) and two vetoes against could play very badly here.

The consequences of any military action

10. A legal justification is a necessary but far from sufficient pre-condition for military action. We have also to answer the big question – what will this action achieve? There seems to be a larger hole in this than on anything. Most of the assessments from the US have assumed regime change as a means of eliminating Iraq's WMD threat. But none has satisfactorily answered how that regime change is to be secured, and how there can be any certainty that the replacement regime will be better.

11. Iraq has had no history of democracy so no one has this habit or experience.

(JACK STRAW)

Foreign and Commonwealth Office

25 March 2002