Robert Fisk: Lebanon slides towards civil war as anniversary of Hariri's murder looms

They were commuter buses, 10 minutes apart, carrying the poor from the mountain town of Bikfaya to the coast, targets of opportunity for someone who wanted to enrage the Christian community of Lebanon less than 24 hours before today's mass demonstrations to mark the second anniversary of Rafik Hariri's murder. Lebanon's killers usually choose the country's politicians, journalists and public figures to destroy but yesterday - in what was obviously intended to be a mass slaughter - they killed a bus driver, a Christian woman and an Egyptian worker. Two bombs packed with metal pellets, hidden under the seats of both buses, by someone who wants a civil war.

All of Lebanon asked itself the same question: was this the attack that was meant to ensure that today's vast protests in Beirut turn violent? For if Beirut passes through the emotions and anger of today's anniversary - the ex-prime minister Hariri was blown up in his motorcade in the city, along with 21 others - without street fighting, then Lebanon may be safe. If it turns into anarchy, then the prospect of civil war looks ever more real. Today, as they say, is the day.

The great and the good of Beirut society were, of course, quick to condemn yesterday's killings. "Another terrorist attempt to exert control over Lebanon with blood and repression," was how MP Nayla Moawad put it. A government supporter, her own husband Rene was blown up only minutes after he was inaugurated as president almost two decades ago.

And Bikfaya - the scene of yesterday's murders - was the home town of the Gemayel family, of ex-president Amin Gemayel who is being hosted by the US government in Washington; of his own murdered son Pierre, shot dead in his car last November. Was this an attempt to strike at the heart of Gemayel's Phalangists? "Alien hands" is how Amin described the murderers.

But they are always "alien hands" in Lebanon, always someone from "outside". That's why the Lebanese still call their civil war "the war of the other". And who is the "other"? The Syrians - always Washington's favourite choice - or the Hizbollah (ditto) or rival Christian groups such as those of General Michel Aoun, who is supporting the Hizbollah's call for the downfall of Fouad Siniora's American-supported government which includes Gemayel and Hariri's son Saad and Christian ex-militia leader Samir Geagea among its loyalists? Or someone who wants Lebanon to believe it was Aoun or the Hizbollah or the Syrians?

Amin Gemayel announced from Washington that "Lebanese don't kill Lebanese" - the same old illusion that has prevented this tortured nation from ever discussing the civil war which killed 150,000 souls between 1975 and 1990 and which now again hangs like one of Lebanon's winter storm clouds, piled up on the horizon, watched and ignored with almost equal fear. The bombs on the commuter buses wounded at least 20 passengers. There were at least 50 people on the two buses; all were supposed to have died.

The first shopkeepers to reach the wreckage found many of them lying screaming on the roadway where they had been blasted from the vehicle.

The first bus to explode - its bent-back roof looked uncannily like the wreckage of the London bus blown up on 7 July 2005 - had just reached the village of Ein Alaq, south of Bikfaya, the windy, cold Christian town in the Metn that is the Gemayels' ancestral home.

Ambulance crews and paramedics had just arrived when the second vehicle - the commuter buses from Bikfaya to the coast run every 10 minutes - approached and blew up. Hundreds of people ran screaming from the highway for fear that there would be a third bomb.

As one witness put it with unconscious irony, "buses don't have political affiliations". But of course, in Lebanon, they do. Everything here has a political affiliation - which is why it is so easy to stir and overheat the sectarian broth.

Today's anniversary will centre around the tomb of Rafik Hariri in the very centre of Beirut, beside the great mosque he built but only 100 metres from the tent city inhabited by the Hizbollah and Aounists and other opponents of the government run by Hariri's old friend Fouad Siniora.

The battle lines have long ago been drawn. Sunni versus Shia, Christian Maronites versus Christian Maronites and - in the case of the Aounists - Maronites versus Sunnis. The word "battle" is a difficult one to write. Every time you use the phrase "civil war" here, you fear that you are helping to bring it about.

Yet the politicians now talk openly of this terrible possibility and the rumours - through every community here - that large amounts of guns are being brought into the city can no longer be ignored.

The discovery by the Lebanese army of a truck load of weapons in the suburb of Hazmieh - weapons that the Hizbollah openly acknowledged belonged to them - caused a small earthquake in the hearts of those who most fear civil conflict.

Why did the Shia group need these guns now? And if these small arms had come from the Bekaa Valley, as apparently they did, why transport them through the mixed Muslim-Christian district of Hazmieh in Beirut? The Syrian government announced only a week ago that they, too, had stopped a shipment of weapons from crossing the border into Lebanon, a bit of law-and-order publicity which many Lebanese found very hard to take but which might well be true.

The Hariri camp has called for "massive" demonstrations today. Geagea, whose thugs once bombed a church north of Beirut in a vain attempt to persuade Christians that they were under attack by the Hizbollah, says that the protests "must be a civilized and peaceful expression of democracy and opinion... in the face of all those who are trying to frighten us". The Sunni Grand Mufti, Sheikh Mohamed Qabbani called for a collective Christian-Muslim prayer at 1pm - the time of Hariri's murder two years ago.

The murdered leader's widow Nazik - a woman of great dignity whom most Lebanese have forgotten is a Palestinian - urged the Hizbollah chairman Hassan Nasrallah to allow the event to unite the Lebanese.