Amid the political debate of recent weeks about the use of ground troops in Kosovo, one of the first tangible signs that a ground war could become a reality came with a statement by Ken Bacon, the Pentagon spokesman.

Announcing the composition of the Task Force Hawk deployment to Albania, he said it would not just include Apache attack helicopters but also their supporting artillery and 2,000 troops.

Besides the 24 Apaches, the force includes M2 Bradley fighting vehicles for protection.

The BBC's Allan Little: "Nato sailing into uncharted waters"

To prepare the way for the Apache helicopters, the US Army is also installing the M270 Multiple Launch Rocket System (MLRS) with its radar, as well as providing CH-47D Chinook and UH-60L Black Hawk helicopters for re-supply and medical evacuation.

The plan is to set up the radar equipment in Albania, but looking deep into Kosovo. The radar will provide targets to the MLRS system, clearing the way for the Apaches to fly in and identify, then destroy individual armoured vehicles.

The Chinook and Black Hawk helicopters will be used to deploy some of the 2,000 US troops which will accompany Task Force Hawk, as well as providing an emergency rescue and evacuation service should anything go wrong.

'All options open'

Calls for more ground equipment and even troops have been coming from analysts, former senior army commanders and politicians in Washington, the European capitals and even the Organisation for Security and Co-operation in Europe (OSCE) which supplied the monitors to Kosovo before the war.

The spectre of having to gather over 100,000 troops and pushing into Kosovo through small roads from Albania and Macedonia is still not on the cards according to senior politicians, but the prime minister Tony Blair has continued to insist that "all options are open."

Besides the political reluctance to commit ground troops, there are problems on the ground. Those problems are not just the difficult terrain and the presence of a heavily armed enemy.

Tension between the Nato allies and Macedonia are running high. The authorities in Skopje have told the US Army that Apache attack helicopters would not be welcome in Macedonia.

President Kiro Gligorov went further and told Nato that his country would not allow Alliance troops to launch an offensive from Macedonia.

Regional preparations

Elsewhere in the region, Nato has been making its diplomatic preparations in case the decision is taken to use ground forces.

The Romanian and Bulgarian governments have agreed to Nato's unrestricted use of their air space.

The Czech Republic, which with Hungary and Poland is one of the alliance's new members, has agreed to allow its territory to be used for the transport of military equipment.

It is vital for Nato to have the flexibity of operations across the whole of the Balkan region, and for this they need to be able to operate across the air space of neighbouring countries without having to obtain diplomatic clearance each time.

And although Nato will not necessarily want to launch an invasion force from Hungary into northern Serbia, it will need to be able to use road and rail links in Hungary and the Czech Republic - at least for logistical purposes. Nato is looking to both countries, as new members, for maximum cooperation.

Serb defence strategy

General Sir Michael Rose, the former SAS commander and general commanding the United Nations forces in Bosnia is adamant that the Serbs would not stand and fight a Nato force.

"Their military doctrine is based on total defence," he says, "that means using the population to help defend the country - and even now in Kosovo, there are still sufficient people who will welcome Nato rather than support the defending Serbs."

While some observers have quoted the four months needed to build up troops and train them for the Gulf ground war, General Rose argues that Kosovo is closer to Nato's home and that the territory is smaller, even if more difficult.

A role is already planned for Apache attack helicopters

Nato, he says, has the benefit of better target acquisition, flexible and highly manoeuvrable warfare as well as better weapons technology. A Yugoslav T-72 main battle tank is no match for a British Challenger, and a Dutch M109 artillery piece can out-shoot one of President Milosevic's M84 long-range howitzers.

With each day of the refugee crisis and weather-restricted bombing, the chances of using ground troops increases. An invasion though is still the last option that Nato wants to consider.

The Serbs have been reinforcing the border, digging-in and placing minefields across the frontier region.

Yugoslavia's military defence plan includes the use of partisan warfare but in Kosovo the remaining local population of Kosovar Albanians are unlikely to want to support a Serb guerrilla army.

The terrain is very difficult, with high mountain ranges surrounding Kosovo, but there are river valleys on the border with Macedonia and Albania which could be used.

The concern is not the geography so much as whether there will be sufficient refugees for whom Nato can give sanctuary. The Nato planners looking at this possibility are said to be carefully crafting a plan which would not look like invasion or occupation.

Lessons of World War II

Officially, the political leadership of Nato has ruled out any opposed ground force intervention because they are simply not prepared for such an operation.

"We would need at least 100,000 troops," said a senior French general last week. In London, military planners say that even more would be necessary.

"Soldiers remember the lessons learned in the Second World War, when seven or eight divisions of German soldiers were tied down in Yugoslavia fighting Tito's Partisan forces. Nobody wants to get back into that situation again - an unwinnable conflict. Planners would need to look at 175,000 at least to ensure victory - and Nato can never be allowed to lose." Nato planners argue that there is no time to prepare troops for such a mission.

"We do not have the right forces in Macedonia," said a senior Nato source. "The troops were originally sent there as an extraction force for the peace verifiers - that mission finished sometime ago and was superseded by the creation KFOR."

KFOR - short for Kovoso Implementation Force - is the Nato-led force, based around the Allied Command Europe's Rapid Reaction Corps (ARRC), led by General Sir Mike Jackson. The mandate under which KFOR's British, French, Italian, German and Dutch troops operate is purely one designed, manned and equipped for peacekeeping.

The lead elements of the formation are provided by the British Army's 4th Armoured Brigade, built up around the King's Royal Hussars battle group with Challenger main battle tanks.

Other British forces include the Irish Guards and King's Own Border Regiment with Warrior infantry fighting vehicles.

German forces, overseas for the first time in 50 years, are operating remotely piloted spy drones, Italian alpine forces have light tanks and attack helicopters, the French have supplied a rapid reaction helicopter force and the Dutch have specialist infantry there.

But this 12,000 strong force is not a force to fight its way into Kosovo.

Commandos 'inside Kosovo'

There are Nato troops in Kosovo already, though, according to French sources.

A Nato soldier on exercise in Macedonia: Equipped for peacekeeping

They say that British and French commandos have been rescuing some prominent Kosovars. French General Jean-Pierre Kelche said he could not exclude the presence of special forces.

That is the closest any Nato officer has come to admitting commandos are operating there.

Senior officials also say that even if ground troops were to go into Kosovo, they would need the same level of air support.

"The Gulf war air campaign took seven weeks and there is no reason why such an operation over Yugoslavia shouldn't take the same timeframe," said a former air chief marshal.

Frustrations grow

Nato senior commanders have become increasingly frustrated with the results of the air campaign.

In private, they have expressed astonishment at being forced to rule out the use of ground troops. Adding more aircraft to the order of battle was not on the original battle plan and is a result of the air campaign not going to plan.

Nato is adamant that at least half the Yugoslav air force has been destroyed and "significant damage" to the Yugoslav war machine.

"There is no doubt that the military want to put a good deal of clear blue water between them and their political masters in Washington and Whitehall," said a senior civil servant in London.

"There has been an increasing feeling that Nato lost the first round to Slobodan Milosevic," he said, "and the senior planners are determined that they will not lose the second round."