Explained | How the Israel-Hezbollah war might lead to broader conflict

Israel has intensified its bombardment of Lebanon, striking what it says are hundreds of sites linked to the Iran-backed Hezbollah group, with Lebanese authorities saying the barrage killed more than 500 people on one day alone. The escalation, after nearly a year of cross-border fire, has added to concerns of a much bigger war between Israel and Hezbollah that could cause major destruction and drag in Iran.

This is how the hostilities between Israel and Hezbollah are playing out:

What's the background to the fighting ?

Hezbollah began trading fire with Israel on October 8, a day after the Palestinian militant group Hamas attacked communities in southern Israel and sparked the Gaza war.

Hezbollah, a Hamas ally, says its attacks aim to support Palestinians who are under Israeli bombardment in Gaza. The Gaza war has drawn in Iran-backed militants across the region. Hezbollah is widely deemed the most powerful member of the Iran-backed network, known as the Axis of Resistance.

While linked to Gaza, the conflict has its own dynamics. Israel and Hezbollah have fought numerous wars, the last major one in 2006.

Israel has long viewed Hezbollah as the biggest threat at its borders and has been deeply alarmed by its growing arsenal, and the foothold it has established in Syria.

Hezbollah's ideology is largely defined by conflict with Israel. It was founded by Iran's Revolutionary Guards in 1982 to fight Israeli forces that had invaded Lebanon that year, and waged years of guerrilla war that led Israel to withdraw from south Lebanon in 2000. Hezbollah deems Israel an illegitimate state established on occupied Palestinian lands and wants to see it gone.

How is the conflict escalating?

Israel's Defence Minister Yoav Gallant said on Sept. 10 the country's operations against Hamas in Gaza were nearly fulfilled and it would soon focus on the northern border, aiming to return thousands of displaced Israelis to their homes. On Sept. 17 and 18 pagers and walkie talkies used by Hezbollah exploded in an apparent Israeli attack, killing scores and wounding thousands.

On September 20, an Israeli strike in southern Beirut killed one of Hezbollah's top commanders along with other senior figures.

Hezbollah fired rockets further into Israel, including at the northern city of Haifa, in retaliation.

On Monday, Israel unleashed its heaviest bombardment of Lebanon of the conflict, focused on the south but also striking targets in the Bekaa Valley and Beirut.

How much worse could it get?

A lot. Despite the ferocity of these hostilities, there is plenty of scope for a much bigger conflict.

Israeli Prime Minister Benjamin Netanyahu warned in December that Beirut would be turned "into Gaza" if Hezbollah started an all-out war. Hezbollah has previously signalled it is not seeking to widen the conflict while also saying it is ready to fight any war imposed on it and warning that it has used only a small part of its capabilities so far.

Past wars have inflicted heavy damage.

In 2006, Israeli strikes levelled large areas of Beirut's Hezbollah-controlled southern suburbs, knocked out Beirut airport, and hit roads, bridges and other infrastructure. Nearly 1 million people in Lebanon fled their homes.

In Israel, around 300,000 people fled their homes to escape Hezbollah rockets and some 2,000 homes destroyed.

Hezbollah has a far bigger arsenal than in 2006, including rockets it says can hit all parts of Israel.

Israeli troops have invaded Lebanon several times in the past, reaching as far as Beirut in the 1982 invasion that aimed to crush Lebanon-based Palestinian guerrillas.

What are the chances of diplomatic solutions?

Israel has said its military operations in Lebanon will continue until it is safe for people in northern Israel to return to their homes - something that would require an end to Hezbollah rocket fire.

Hezbollah has said it will keep firing while the Israeli offensive in Gaza continues.

However, Gaza ceasefire talks have stalled with little sign of progress soon. The US does not support the escalation between Israel and Hezbollah across the border, a senior State Department official said, but Washington has stopped short of publicly putting pressure on Israel to ease its bombardment.

The US official at the heart of diplomatic contacts, Amos Hochstein, brokered an unlikely diplomatic deal between Lebanon and Israel in 2022 over their disputed maritime boundary. At the start of the year, Hezbollah signalled its eventual openness to an agreement that benefits Lebanon, but said there can be no discussions until Israel halts the Gaza offensive. Hochstein said on May 30 he did not expect peace between Hezbollah and Israel but that a set of understandings could remove some of the impetus for conflict and establish a recognised border between Lebanon and Israel. A French proposal submitted to Beirut in February included elite Hezbollah fighters withdrawing 10 km from the frontier and negotiations aimed at settling disputes over the land border.

The prospect of implementing any such deals looked dim even before the latest round of escalation. It now seems less likely still.