Hundreds of miles from the battle front amid the long corridors of Nato's military headquarters, General Wesley Clarke is in charge of a campaign which is not exactly going to plan.

This operation may have the best technology, but there is a feeling at Nato HQ - conveyed only privately - that it is not Nato which is making the running, but Mr Milosevic.

The BBC's David Shukman: "The military campaign is not exactly going to plan"

In public of course, the line remains upbeat.

"We never thought we could fight a ground war from the air," said Allied Supreme Commander Wesley Clarke.

"But we do know that we're making them pay a heck of a price for the terrible things that are going on, and we intend to continue and intensify that.

RAF Harrier GR7s are trying to find Serb tanks

"I think very clearly from the air side we have the initiative".

But nothing is quite that simple, as the RAF Harrier pilots are finding out.

Armed with cluster bombs, they have been sent to attack the Serbs tanks in Kosovo - the central part of the Nato campaign.

The weather is clear for bombing now, but the Serbs have suddenly become elusive.

They have spread their forces out over Kosovo, and are hiding them in and amongst buildings and also under camouflage, where the tanks are kept static. In this way they save the fuel which Nato is trying to deny them by bombing supplies.

Nato frustration

They maintain radio silence so they are harder to track, and not using their engines means there is no heat signal for Nato's infra-red cameras to track.

Air Commodore David Wilby expressed his frustration

At the Nato news briefing, Air Commodore David Wilby admitted that he faced frustrating problems.

"Despite the good weather, we did have problems actually seeing the targets and being able to get them on the ground," he said.

"It is a very cunning enemy out there", he said.

It was in the heart of Nato's military headquarters that the original war plan was drawn up, but it is clear that has now been overtaken by events on the ground.

Nato is suddenly having to operate on two fronts - the military and the humanitarian. It is having to come up with a new plan, but that is far from easy.