President Clinton is in Europe to try to bolster support for the Nato air campaign against Yugoslavia - an operation that few expected would still be under way after so long.

Mr Clinton's itinerary has included a visit to Nato headquarters, meetings with US personnel involved in the Kosovo campaign, and talks with the German Chancellor, Gerhard Schröder.

Nato strikes are in the seventh week

The air strikes, now in their seventh week, have been intensifying and, against that background, it was perhaps inevitable that the pace of diplomacy would quicken.

Nato tactics

As the military operation has unfolded, so inevitably Nato leaders have been focusing more closely on how exactly the conflict might be brought to a conclusion.

Hence, in part, President Clinton's reference to a possible pause in the action if there is a sign that President Milosevic is ready to accept Nato's demands.

The Alliance has said it is ready to look at negotiations about implementing these demands - for example, how the Serbs might withdraw their forces from Kosovo. But it is insisting there can be no compromise on the substance of the demands. The message from President Clinton seems to be the same.

Political pressures

There is, however, growing political pressure on the Alliance. Recent votes in the US Congress have underlined deep divisions over the operation, and its conduct.

The outgoing Chairman of Nato's Military Committee, General Klaus Naumann, has voiced the frustrations of many commanders that Nato has been constrained too much by the drawbacks of trying to run a campaign on behalf of a coalition of 19 nations. They believe it should have been more forceful sooner in its military operations.

Nato strains

Chancellor Schröder says there is no reason to change Nato's bombing strategy

The length of the campaign is also increasing political strains in other Nato countries, not least Germany - one reason for Mr Clinton's talks with Chancellor Schröder.

On the diplomatic front, the talks between the Americans and the Russian envoy, Viktor Chernomyrdin, are said to have produced some progress.

The key issues remain the nature of an international presence in Kosovo, and the details of a Serb withdrawal.

Russian mediation

The Russians have been attempting to bridge the gap between Nato and Belgrade on both these fronts. But that gap remains a huge one, and Nato and Russia themselves remain somewhat at odds.

The United Nations is also likely to play a part in any final settlement. An international force could be under the auspices of the United Nations. But the Alliance still insists the international presence must be an effective military force - which means it must have Nato at its core, albeit that other nations, including Russia, could play a part.