Leading Article: The crossing of a Rubicon

AT LAST, public opinion has had its effect. For months the British and US governments stubbornly opposed any form of military intervention in Bosnia-Herzegovina. Now they are understood to have reached agreement with the more militant French on a draft United Nations resolution that would sanction the use of all necessary means to ensure that humanitarian aid gets through to those who need it. Both Nato and the Western European Union are likely to be involved in providing the necessary means.

The change of heart is belated. After all, the vile policy of 'ethnic cleansing', preceded where necessary by weeks of siege and heavy bombardment, has been in operation for months. Practised mainly by the Serbs but also by the Croats, it has so far driven some two million people from their homes. It was the horrors of the Serb-run detention camps that wrought the transformation. Public outcry in the West forced the politicians to overcome their fears of the quagmire effect of involvement. With the unfolding of the tragedy regularly predicted a year ago, it has been a deeply unimpressive performance. There remains a danger that a UN-backed operation will go seriously wrong unless it is carefully conceived and planned. If a minimalist and reactive approach is adopted, as seems likely, the outcome could be not just unsustainable but disastrous.

The concept of all necessary means (first used to sanction the use of force in the Gulf) is as flexible as could be desired. But a far- sighted collective strategy will be needed to define what measures may be required to achieve whatever goals are defined. Lawrence Eagleburger, the US deputy Secretary of State, begs the question when he says: 'The President, in talking about all necessary means, including the use of force, is talking exclusively about using that to provide humanitarian assistance.' No effort, he indicated, would be made to 'end the civil war'.

Mr Eagleburger and Mr Bush are surely mistaken. What is taking place in Bosnia is not a civil war in the normal sense. The movement of populations is not a product of fighting between two sides, but the primary purpose of a campaign of terror and territorial annexation. Bosnia's UN ambassador, Muhamed Sacirbey, is justified in accusing Messrs Bush, Major and Mitterrand of trying to salve public opinion by dealing with humanitarian aspects while failing to face up to the root cause: the policy of ethnic cleansing directed from Belgrade. With the UN arms embargo perpetuating the Serbs' huge military superiority, his plea for weapons also deserves sympathy, as Baroness Thatcher has been underlining with commendable forcefulness in the US.

For all these reasons, a minimalist strategy limited to escorting aid convoys is likely to prove not just inadequate but dangerous. What would happen, for example, if a humanitarian convoy and its military escorts were ambushed from nearby hills and wiped out by mines, mortar and machine-gun fire? A few such attacks would soon persuade those providing the escorts to assume the initiative. If military supplies were coming in from Serbia, targets there would need to be attacked. In agreeing to use all necessary means, Britain, France and the US will have crossed a Rubicon. But they do not seem to realise they are about to do so.