Sir, We watch the deteriorating security situation in Iraq with deep sadness.

The coalition forces should have only one purpose: to promote the rule of law in a chaotic post-conflict environment. The military must not themselves be above the law; we learnt that lesson in our own prolonged counter-insurgency operation in Northern Ireland. British soldiers are not naturally more restrained than their American cousins. Hard training and discipline have instilled into them the importance of working within the constraints of normal civilian law when trying to build trust with the community.

If we seek to bring democracy to Iraq, the rule of law should come first; and coalition forces must be just as subject to it as are the ordinary citizens. This means that often a direct military response will be disallowed in favour of a more peaceable solution of a police nature.

This is always a hard lesson for the military to learn. The Northern Ireland peace process would not have been helped by the use of attack helicopters against IRA strongholds. Israel degrades its security with each use of excessive force in Gaza. Likewise, bombing mosques or strafing houses makes any settlement in Iraq more difficult to achieve.

We strongly believe that all forces in Iraq should be required forthwith to act within the confines of normal civil legal rules. After power is transferred on June 30, any agreement on the status of foreign forces with the new transitional government must require that the military operate within the law.

Yours, TIMOTHY GARDEN (Assistant Chief of Defence Staff, 1992-94), JOHN STANIER (Chief of the General Staff, 1982-85), BRYAN THWAITES, HAROLD WALKER (Ambassador to Iraq, 1990-91), Centre for Defence Studies, King's College London, WC2R 2LS timothy.garden@kcl.ac.uk