Why are Israeli forces in southern Lebanon?

The Israelis say they need a military presence in Lebanon, in what they call a "security zone", to deter attacks on Israel by militants based in Lebanon. Arab states denounce that presence as an illegal occupation.

Israel first established a buffer zone along the border in March 1978, in retaliation against raids by Palestinian fighters.

After invading Lebanon with more than 20,000 troops, the Israeli Defence Force (IDF) pulled back, leaving a proxy militia (see below) to patrol much of the captured territory.

A second Israeli invasion took place in 1982, again in response to Palestinian raids.

The IDF advanced as far as Beirut before becoming involved in fighting with the Syrian army and air force.

Following a ceasefire, and the expulsion of the Palestinian leadership from Lebanon, Israel again withdrew, but this time left its own troops to maintain the "security zone".

What is the South Lebanon Army (SLA)?

The mainly Christian SLA militia is armed, trained and financed by Israel.

Antoine Lahad: 15 years as SLA chief

Formed during the Israeli occupation of southern Lebanon in 1978, the SLA was originally commanded by a former Lebanese army officer, Saad Haddad.

When he died in 1984, Israel appointed Antoine Lahad as his replacement; he still leads the SLA.

What is Hezbollah?

Hezbollah ('the Party of God') emerged as a political and military force in the early 1980s, its raison d'etre the second Israeli invasion of Lebanon.

Sheikh Nasrallah: Hezbollah leader

According to its manifesto, its "Islamic resistance units" are fighting "for the liberation of the occupied territories and the ejection of the aggressive Israeli forces".

Hezbollah's Secretary-General is Sheikh Hassan Nasrallah, a Shiite cleric.

The guerrillas have received ideological inspiration and financial assistance from Iran, and have been denounced by the United States as a terrorist group.

The Lebanese Government, influenced by Syria (see below), has tended to treat Hezbollah as a counterweight to the SLA, and has not disarmed the guerrillas.

What is the Syrian connection?

After the protracted and bloody civil war in Lebanon, Syria emerged as the real power-broker in its smaller neighbour.

Hafez al-Assad: Controlling Lebanese politics

To this day, no major political decisions are taken in Beirut without approval from Damascus.

It is widely believed by diplomats in the region that President Assad of Syria is using Hezbollah as a proxy militia to put pressure on Israel and its own proxy, the SLA, in southern Lebanon.

What are the United Nations doing on the ground?

The UN Interim Force in Lebanon, Unifil, has been on the ground since 1978. It now consists of 4,500 troops from 10 countries, under the leadership of Major-General Jioje Konouse Konrote of Fiji.

Established to confirm the withdrawal of Israeli forces from the area, Unifil says it has been "prevented from fully implementing its mandate".

But Unifil says it does its best to limit the conflict and protect local inhabitants.

What are the prospects for peace?

The new Israeli Prime Minister, Ehud Barak, made strategic withdrawal from Lebanon a major issue in his successful election campaign.

Many Israelis, depressed by the deaths of IDF personnel, have called for an end to the occupation.

The logic of occupation has in recent years become something of a Catch-22, with Israel saying it needs the buffer zone to deter Hezbollah rocket attacks on Galilee, and Hezbollah saying it is only attacking Israel because of the occupation.

But it seems likely that the conflict can only be ended if and when the Israel-Syria track of the Middle East peace process is revived, and all sides see political benefit in ending the violence.