Leading Article: . . . another holds much promise

THE growing pressure to declare a no-fly zone in Bosnia-Herzegovina is concentrating minds wonderfully. It explains, in part, the flurry of meetings this weekend at the UN's European headquarters in Geneva. It also helps to explain the opportunistic message from Radovan Karadzic, the Bosnian Serb leader, who has written to John Major, assuring him that all flights in the areas concerned are humanitarian, and offering to allow UN monitors to verify this claim. Less than a fortnight ago Mr Karadzic was blustering about the likelihood that his 'parliament' would regard any attempt to enforce the no-fly zones as an act of war. UN ground troops would then be forced to leave Bosnia, he warned.

The Serbs in northern Bosnia are not as formidable as they sometimes seem. The rapid initial advance of their fighters early last summer was largely the result of surprise, the systematic use of terror and the fact that the Muslims were poorly armed. The Serbian forces act with great ruthlessness but do not constitute a highly motivated or well-disciplined fighting force. Their commanders lack military sophistication. Evidence is mounting that the position of the Bosnian Serb fighters is precarious, and becoming more so as the performance of the Muslim forces improves.

If the Muslim successes that we report today are sustained, Serbian supply lines sustaining the forces occupying the northern part of Bosnia may soon be cut. Air transport will then become not merely important, but crucial. The severe disruption of agriculture in the area (partly as a result of 'ethnic cleansing') has meant that the occupiers depend heavily on food from Serbia.

Strict enforcement of the no-fly zone could almost certainly do serious damage to the Serbian cause, in spite of the largely correct claim that Serbian planes have not carried out combat missions in recent weeks. The importance of helicopter and other flights has increasingly been to deliver munitions, food and other supplies from Serbia to the Bosnian Serbs who have seized control of almost 70 per cent of Bosnia, encircling the Muslim heartland.

However, the UN Secretary-General, Boutros Boutros-Ghali, and the joint chairmen of the UN initiative, Lord Owen and Cyrus Vance, are reported to believe that rapid and strict enforcement of no-fly zones might endanger the current search for a constitutional settlement in Bosnia as well as endangering efforts to aid civilians.

If this is their considered judgement, it should be treated with respect. But that would not be incompatible with passing a Security Council resolution of the type which the United States hopes to achieve within a matter of days. Such a resolution might, for example, carry no deadline, thus leaving the UN forces free to impose one at their own discretion. Or it could say, as did the UN resolutions authorising force in Iraq, that force could be used after a stated date.

The essential point is that psychological pressure on the Serbs should be steadily increased. For example, speculation that the Western powers might permit a limited relaxation of the arms embargo that has borne unfairly on the Muslim side could be productive. Experience shows that the Bosnian Serbs are free with their promises, but deliver only under pressure.