Five years after the fall of the Berlin Wall, there are encouraging signs that Nato is developing imaginative responses to the world's new security challenges. It is not before time. Fairly or not, the impression was gaining ground in Western cou ntries that Nato was proving incapable either of tackling serious crises, such as that in the former Yugoslavia, or of reforming itself sufficiently to take account of the transformations in the international order.

A low point was reached last November, when one of the worst rows between the United States and its European allies broke out over how to react to the Serbian assault on the Bosnian enclave of Bihac. The new ideas now taking shape in the Nato countries, and explained in this paper's interview with Willy Claes, Nato's secretary general, go a long way towards defining a future role for the alliance. They shouldinject it with a fresh sense of purpose.

There are four specific proposals. The first is the creation of a permanent commission between Nato members and Russia that would discuss European security in general and specific crises such as the Balkan conflicts. The idea is to ensure that the West springs no surprises on Moscow and avoids precipitating a Russian retreat into aggrieved isolation. It is an intelligent initiative, and one that would justify the second proposal - to expand Nato by admitting the Czech Republic, Hungary, Poland and Slovakia. No one, including the Russians, benefits from a security vacuum in central Europe. However, the West should entertain no illusions about the stiff resistance that Moscow will continue to mount against Nato's enlargement. If the alliance is to expand, the proposed Nato-Russian commission must be no mere cipher.

The third idea is that Nato should arrange security links with friendly and moderate countries in northern Africa and the eastern Mediterranean. The aim is to counter extremism and instability in the region, where the Algerian civil war is only one manifestation of growing political and social strains. As the French have long argued, this region is more than a southern European concern, since developments there are intimately related to events in the Middle East and the Gulf. Nato engagement in the areacould also reduce the risks of terrorism and proliferation of weapons of mass destruction.

The final idea, and perhaps the boldest, is the reorganisation of the US-European alliance into a transatlantic community united by commercial, monetary, political and cultural ties, as well as by the existing military relationship. Admittedly, with precise details not yet worked out, it sounds somewhat vague. But at least the proposal appears to address Nato's main problem since 1989: the need to redesign the alliance without forsaking the collective security guarantee that has been one of its greateststrengths over five decades.

As an alliance of democracies and the most powerful military bloc in history, Nato has a special responsibility to find answers to the questions posed by the revolutionary changes in the world over the past five years. After an uncertain start, there aregrounds for hoping that Nato may be getting some of the answers right.