"What is the Sudan problem?", asked the visiting journalist. "Is it the North against the South?"

"It is not," replied his host.

"Is it the Arabs against the Africans? Or the Islamic government against the rebel Sudan People's Liberation Movement? Or even the Muslims against the Christians and Animists?" he inquired.

"It is not."

"Then what is it?" said the journalist, exasperated.

"It is all of these things - and more."

The truth is that anyone who thinks he understands Sudan doesn't really know what is going on. The country straddles the fault-line separating the worlds of Islam and Christianity. It has inherited the legacy of a brief but bitterly divisive colonial past. Vast oil reserves lie in the ground, waiting to be exploited by whichever side wins the civil war.

That is, if any side wins. War has become a state of mind in these parts - it is simply the way things are. For all but a decade of its 42-year existence as an independent state, Sudan has been consumed by ruinous conflict. Millions have died and the warlords have prospered.

As colonist, Britain encouraged the separation between the Islamic North and the "African" South. But in 1956 it responded to the clamour for independence by dumping both parts into a state half the size of the US.

From independence the light-skinned Arab elite in Khartoum tried to Arabise and Islamise the entire country, and the south resisted. Successive northern governments grew ever more fundamentalist, introducing sharia Islamic law and sponsored acts of terror abroad by Islamic extremists.

Southern opposition has been characterised by frequent splits and in-fighting, although the SPLM leader, John Garang, has managed to fashion an efficient fighting force out of disparate elements.

Yet the SPLM has also shown a recurring knack for snatching defeat from the jaws of victory, so most observers expect the civil war to continue. It is no coincidence that those areas of southern Sudan most threatened by famine are also the scene of the fiercest fighting.

Indeed the catastrophe in the worst-affected area, Bahr El Ghazal, can be traced directly to the offensive launched in the area last January by a maverick and brutal warlord, Kerubino Kuanyan Bol.

The result this year is four million people who have been forced to flee from their homes, 2.5 million in danger of severe hunger and about half a million in need of immediate assistance.