What would a war between Israel and Hezbollah look like?

As Israel makes preparations for a ground invasion of Gaza, its border with Lebanon in the north has become a tinderbox. Skirmishes between the powerful Lebanese militant group Hezbollah and the Israeli army have ruptured the relative calm that has held between the two enemies for some years.

Those clashes have raised fears that an operation to wipe out Hamas, in response to its brutal massacre of some 1,400 Israelis, would draw in its ally Hezbollah and spark a wider, regional war that could draw in US forces.

So what does Hezbollah want? And what will determine whether it joins the fray? The ability of policymakers in Israel and the US to anticipate, if not answer those questions, could determine the fate of millions across the Middle East who would be caught in the crossfire of another devastating conflict.

At the heart of these calculations is a view held by both sides that the current Gaza crisis is just one part of a greater proxy war between rivals Israel and Iran. The Islamic Republic has spent years building a network of allied militant groups opposed to Israel under a concept referred to as “unity of the fronts”. Those groups – which include the Syrian government, Hezbollah in Lebanon, Hamas in Gaza, Houthi rebels in Yemen and various Shia militant groups in Iraq and Syria – have been furnished with military training, financial support, missiles, and the ability to make their own missiles. All of them could be drawn into the conflict if fighting breaks out between Hezbollah and Israel.

To understand the current risk of conflagration between Hezbollah and Israel requires looking to the past, to the conclusion of the last major conflict between the two. The 2006 war defined an unspoken set of rules that allowed a certain level of confrontation while reducing the risk of escalation into a full-blown war. Those rules are now being stretched to breaking point.

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On 26 July, 2006, a quiet morning in northern Israel was abruptly disturbed by a sudden barrage of Katyusha rockets fired from across the border in Lebanon. At the same time, a few miles away, Hezbollah commandos infiltrated the usually impenetrable border and hid in the brush by the side of a road, where they waited to set their trap. When a pair of Israeli army humvees approached, they unleashed a flurry rocket-propelled grenades and heavy gunfire. Before the morning was out, the Hezbollah team had killed three Israeli soldiers and had taken two more hostages back into Lebanon.

The Israeli response to that operation 17 years ago – which foreshadowed a far more brutal attack by Hamas this month – would be swift and devastating. Israel launched a full-scale invasion of southern Lebanon that aimed to impose costs not just on Hezbollah, but on the Lebanese government and its citizens.

When the dust had settled, the balance of power in the Middle East had been dramatically altered, but not in the way Israel had hoped. The 34-day war led to the deaths of 1,200 people in Lebanon, mostly civilians, and 157 Israelis, mostly soldiers. Israel attacked Lebanon’s infrastructure and displaced more than 1 million people, but Hezbollah emerged emboldened and claimed victory, for surviving, and for continuing to fire rockets throughout.

Since then, Hezbollah has become stronger still. It has gained valuable fighting experience on the battlefields of Syria’s civil war, its stockpile of Iranian-made and self-produced rockets has never been higher and their capability has improved, according to Michael Knights, a fellow at the Washington Institute and expert on Iran-backed militias.

“Israel says the Hamas attack involved about 1,500 commandos entering Israel: Israel has assessed that Hezbollah has a 45,000-strong regular army,” he told The Independent. “Hamas fired about 3,300 missiles and drones so far: Hezbollah has around 150,000 munitions ready to fire.”

The 2006 war was costly to both sides, and they have gone to great lengths to avoid another widespread outbreak of hostilities in the intervening years. Firas Maksad, senior fellow at the Middle East Institute in Washington DC, told The Independent that an “unwritten understanding” has developed between the two sides to avoid another war, at least inadvertently. This “delicate game” as he describes it, can involve quite serious clashes along the border.

“I think it’s important to remember that the two parties have had a 40-year history of confronting each other across both sides of that border, which has also lent itself to a better understanding of each other’s intentions and objectives,” he said.

“The big question here, in the coming days, is whether there is going to be room for misunderstanding and miscalculation. Tensions are definitely very high,” Mr Maksad added.

Western policy makers will no doubt be watching the border and listening carefully to the words and rhetoric coming from Hezbollah and its sponsor, Tehran. Both have signalled that a ground invasion of Gaza may provoke a wider intervention.

Speaking to the Associated Press this week, Qassim Qassir, a Lebanese analyst close to the group, said Hezbollah “will not allow Hamas’ destruction and won’t leave Gaza alone to face a ground incursion”.

“When the situation requires further escalation, then Hezbollah will do so,” he added.

Iran’s foreign minister said that a “preemptive action” against Israel could be expected if it pushed ahead with its operation in Gaza.

“Leaders of the resistance will not allow [Israel] to take any action in Gaza. All options are open and we cannot be indifferent to the war crimes committed against the people of Gaza,” Hossein Amirabdollahian, told state TV on Monday.

This week, US forces in Iraq and Syria have already come under attack by suspected Iranian-backed militias. And on Thursday, US officials said a US warship intercepted multiple projectiles near the coast of Yemen. They added that the missiles were fired by Iranian-backed Houthi militants, suggesting that the group might also become engaged in the fighting.

Iran may have already started to activate some of its proxies throughout the region, but when it comes to Hezbollah’s full entry into the war, precisely how the decision is made, and by whom, is somewhat different. Thanassis Cambanis, senior fellow and director of Century International, told The Independent that many politicians in the West make the mistake of assuming Hezbollah takes all of its orders from Iran.

“Hezbollah is not a simple proxy or simple puppet. It is an autonomous organisation with its own power and its own political calculation that is very tightly and inextricably bound with the regime in Iran,” adds Mr Cambanis, author of A Privilege To Die, a book about Hezbollah.

“If Hezbollah’s constituency feels that Israel is putting too much pressure on Lebanon and Hezbollah, or is going too far in its war crimes against Palestinians, that’s a major factor. And the other is whether Hezbollah feels it is strategically poised to gain some advantage in his ongoing renegotiation of its balance of power vis-a-vis Israel,” he says.

The Biden administration is taking the threat of Hezbollah’s involvement seriously. Since the latest Gaza war began on 7 October, it has moved two aircraft carriers to the eastern Mediterranean – a show of force intended to dissuade Iran and its allies from involvement. The president had a direct message for Hezbollah and Iran when asked about the possibility of escalation: “Don’t, don’t, don’t, don’t.”

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Hezbollah was forged in the fires of the brutal Lebanese civil war. That shifting conflict, fought from 1975 to 1990, pulled in almost every major and minor power in the region. When Israel invaded in 1982 to destroy the Palestine Liberation Organisation once and for all, a group of Shia fighters and clerics influenced by Iran’s theocratic government – named the Party of God – took up arms against it. Iran’s Revolutionary Guard saw an opportunity to export its Islamic Revolution and began funding the group, starting an almost symbiotic relationship that lasts to this day.

In the aftermath of the 2006 war, Hezbollah’s popularity reached a peak across the region as it emerged as the most powerful challenger to Israel’s dominance in the region. At home in Lebanon, however, it has long been viewed as an oppressor as much as a liberator.

The tension between Hezbollah and the Sunni community in Lebanon and beyond only grew when Hezbollah entered the Syrian civil war to bolster Bashar al-Assad’s forces. Hezbollah acknowledged its presence in Syria in 2013 but is suspected of operating there since 2011. The group sent thousands of fighters to crush what was primarily a Sunni uprising against the Syrian dictator.

The group’s leadership is also notoriously secretive. Its leader, Hassan Nasrallah, has rarely been seen in public since the 2006 war, and decision making is concentrated to a select few senior figures. That secrecy, and the group’s own mythmaking, has given it an aura of mystique that it has used to its advantage over the years.

All of which leaves plenty of room for miscalculations on both sides.

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Although Israel has made clear publicly that it would prefer not to fight a two-front war, it has mobilised its forces to the northern border in preparation for one.

Israel’s defence minister Yoav Gallant told reporters on 15 October that Israel had “no interest in a war in the north. We don’t want to escalate the situation”.

That may not be enough to convince Hezbollah leaders that it is next in the firing line, however. At a time when Israel has been given the full backing of the US, some in Hezbollah may feel that it is only a matter of time before the Israeli army turns its attention north.

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“I think Iran will continue to use asymmetric warfare to extract a price from the US and Israel, and the US is not particularly equipped to respond to that type of warfare. Two aircraft carriers off the coast of Lebanon do not really help much in terms of that kind of fighting,” Mr Maksad says.

“But I do think that they might succeed in deterring an all-out war,” he adds, while conceding that there are risks to this game.

“We’re seeing a game of attempted mutual deterrence. It’s dangerous because while both sides are arguably trying to deter each other and don’t want to see a full-scale regional conflict, that kind of posturing might lead to that regional conflict that all sides don’t want to see.”

If it cannot prevent that from happening, what would a war between Israel and Hezbollah look like?

The biggest difference from 2006 is Hezbollah’s stockpile of precision missiles, which has grown substantially.

“This will allow Hezbollah to target Israeli bases, perhaps retaliate against the destruction of Lebanese infrastructure by targeting Israeli infrastructure,” says Mohanad Hage Ali, deputy director for research at the Carnegie Middle East Centre.

He adds that new technologies that weren’t widely used in 2006, such as drones, might impose greater costs on Israel, too.

“It would give them a bit of a leeway to force Israel into accepting a quicker end to the conflict. But given the current political mood in Israel, I think that would be a challenging goal for Hezbollah,” he adds.

There has also been discussion among US and Israeli officials about the possibility of US forces actively engaging Hezbollah in some way, Axios has reported. The officials said the type of response would be determined by the scope of Hezbollah’s attack, if it came.

One thing is for certain, however. Just as Israel’s war in Gaza has been the deadliest of any previous attack – some 3,785 people have been killed there since the war began, the majority of them women, children and older adults, according to the Gaza Health Ministry – a war between Israel and Hezbollah would likely cause mass civilian casualties on both sides.

“A new war between Hezbollah and Israel would cause catastrophically more harm to civilians than the last war between the two parties in 2006,” Mr Cambanis says. “Both sides have much greater military capability than they did in 2006 and much more political incentive to maximise the harm they cause to the other side.”

“Both Hezbollah and Israel have a track record of indiscriminately targeting civilians in their conflicts with each other, and on the Lebanese side we have a population that is much more vulnerable and lacking resilience than it had in 2006 because of the degradation of the last four years of economic crisis,” he adds.