Some 400 Nato aircraft are at a high-level of readiness waiting to be unleashed on the Yugoslav Federal Army if western politicians decide to go ahead with their threats against President Milosevic.

These are backed up by at least six US warships in the region capable of launching cruise missiles.

US spokesmen say additional F-15 aircraft could be moved rapidly to Italy from other bases in Italy if the decision is taken to launch air attacks.

BBC World maps out Nato's military options

The United States also has at its disposal ultra-modern F-117 stealth fighters, long-range B-52 bombers, EA-6B radar-jamming aircraft and air-to-air refueling planes.

The Yugoslav army, meanwhile, has moved a small number of tanks into Kosovo, and the US Defence Department estimates that there are some 14,000 to 18,000 Yugoslav troops in Kosovo itself, and perhaps as many as another 20,000 around the perimeter of the province.

Cruise missiles

There is no doubt that Nato is quite capable of unleashing a punitive and damaging attack against President Slobodan Milosevic's forces in Kosovo.

Plans for such an air campaign were all in place last October.

The war planes currently on alert at Nato bases facing the former Yugoslavia across the Adriatic could be rapidly reinforced.

The only limiting factor on Nato's actions would be the need to withdraw all of the unarmed OSCE monitors from Kosovo in advance of any military action.

There are some 12,000 Nato troops in Macedonia - the advance element of the force that would go into Kosovo if a deal is reached.

The Nato troops also stand ready to extricate the monitors if they get into trouble.

The targets

Nato Secretary General, Javier Solana, has emphasised that military action might be broad in scope and not confined to targets in Kosovo itself.

A phased air campaign would hit fixed Yugoslav army installations - missile sites, command centres and supply dumps, and it could go on for several days if President Milosevic failed to bow to Nato's demands.

Clearly air defence sites would be among the initial targets; but the initial attacks could be limited, with Nato ratcheting up the pressure as the campaign went on.

'When the smoke clears'

But the Alliance knows that this is a high-risk strategy. The ethnic Albanian separatist movement - the KLA - might well seek to take advantage of the Nato air strikes to step-up its own activities against Serbian forces.

Nato is not seeking to go to war with Slobodan Milosevic, but to pressure him to give way.

Tens of thousands have been made homeless since the offensive began

It is an uncertain and unpredictable strategy. And the real dilemma facing Nato is not so much the launching of air strikes, but what would happen next once the smoke clears.

If some semblance of order were to be restored in Kosovo an armed international presence might well be needed on the ground. That means Nato combat troops. They could be in Kosovo for a very long time.

It is something Nato leaders do not want to think about for now, but Alliance ambassadors know that air strikes without some long-term strategy would make little sense.

Peacekeeping force

If a deal is reached, somewhere between 20,000 and 30,000 Nato troops might be required to keep the peace in Kosovo during any interim political settlement.

Nato has made clear it will only send a force into Kosovo once a peace deal is accepted by all sides.

But it could have troops on the ground in Kosovo - perhaps occupying Pristina airport - within 48 hours of any agreement.

This would essentially be a light force based on the Nato troops currently in Macedonia, together with US Marines and headquarters elements.

But Nato could have tanks and artillery in place within about a week of a bargain being struck.

If a settlement does emerge from the talks, Nato realises that, while any force it deploys might be scaled down over time, it will probably have to remain in Kosovo for anything between three and five years.

A key factor will be the exact wording of any peace deal. The Dayton agreement on Bosnia contained a powerful annexe giving Nato-led troops considerable freedom of action.

Nato commanders would like similar undertakings to be written into any Kosovo deal.

The Americans want a smaller commitment than they had under the Dayton process. They know that to some extent they can trade absolute numbers on the ground against logistical and intelligence support.

Command of any operation would be given to the Nato Rapid Reaction Corps which is headed by a British officer, but ultimate command would be vested in the Supreme Allied Commander Europe who is an American.