"How are you preparing for NATO air strikes?" "I think I'll be spending a quiet air strike at home with the family." This joke and others are doing the rounds in Belgrade as people wait for Nato to decide whether it will use force in an effort to compel Serbian leader, Slobodan Milosevic to withdraw troops from Kosovo. While some people sit glued to the radio or television, others are taking the philosophical view that it is pointless to worry about a decision which they cannot influence.

Turning on Serbian state television this week, you get a feeling of deja vu. In a throwback to the days of Communism, the main channel is broadcasting a commercial for the army. Every few hours rousing music comes from the box and patriotic images flicker across the screen.

It is a mixture of the gung-ho and the emotive. A shot of Serbian children in a meadow cuts to a camouflage-clad platoon striding towards you in slow motion. The visual extravaganza is set to lyrics promising your army will watch over you.

On a more mundane level, town and city authorities in most of Serbia are testing their air-raid sirens. The system dates back to the 1950s and serious maintenance work is needed. A defence ministry official admitted many sirens did not function because of faults or missing parts. Some had disappeared altogether. The authorities in Belgrade decided against carrying out a dry-run of the air-raid warning system, for fear of creating panic.

The people of the capital are convinced it's only a matter of time before the bombs start falling. The conversation in cafes and at home has switched to weighty questions. Will Nato give us any warning before they bomb?

When - or rather if - we hear the air-raid siren, how much time will we have to take cover? It's useless trying to explain about clinical strikes on military installations, people are convinced the bombs will be landing on their heads. Such is the fear of air strikes that when Belgrade was shaken by an earthquake last week, many people thought it was Nato bombers. One woman jumped from her balcony into the garden, after hearing what she thought was the drone of planes.

All of this has led to a sudden enthusiasm for the old concrete bunkers left over from the civil defence infrastructure of Communist times. Like the air-raid sirens, these ugly edifices have up to now been viewed as obsolete and even a bit of a joke. But the bunkers have not been lying idle: some enterprising individuals have found new uses for them. So you can have your hair cut at a bunker barbershop, dance at a bunker disco or work out in a bunker fitness centre. But the plug is about to be pulled on these businesses. Citizens are eager to reclaim the bunkers, although the supplies of emergency provisions which used to be kept there are long gone.

People are stocking up on food as if preparing for a medieval siege. Shortages of staple goods like cooking oil, sugar and flour are common in Serbia, so the current crisis is making a bad situation worse. If you go into a state-run shop in Belgrade you are greeted by bare shelves. There's been a run on non-perishable items like tinned food and biscuits. You can still find goods in private shops but at 50 per cent above the official price. A new war tax has been introduced which is pushing up prices still further.

People power in the shape of newly-formed crisis committees is supplementing the official efforts. The crisis committee in the northwestern town of Novi Sad has been hard at work. Within two days of forming it proudly announced that it had collected enough food to enable the citizens of Novi Sad to survive a two-month siege.

The anxiety about being the target of a Nato attack is strongest in towns or villages where there are military bases. Some people have complained that the authorities have not given any indication about where Nato might strike. "Will they bomb only radar sites or could our local barracks also be a target?" They don't stop to think that the authorities must be asking themselves the same questions.

Towns which house big military centres are taking special precautions. The town of Kragujevac, 130 miles south of Belgrade, has what it now regards as the misfortune of being the location of three barracks and an arms factory. It is also a staging post for army conscripts being sent down to Kosovo. With the threat of air strikes, the local hospital has decided to discharge all but emergency cases, in order to free up beds for potential casualties.

In public at least the Serbian strongman, President Slobodan Milosevic, carries on as if oblivious to the sense of impending gloom gripping everyone else in the country. The main evening news on state-run television earlier this week was positively surreal. On a day when the Nato storm clouds had been gathering, the first news item showed President Milosevic greeting a delegation of smiling children from all over eastern Europe, colourfully dressed in national costume.