Israel is pushing Hezbollah to its limits. How it responds will define the future of this war

With the assassination of Hamas official Saleh al-Arouri in Lebanon, Israel has risked an alarming escalation

In an alarming turn of events, just as Israel revealed its plan to withdraw thousands of troops from northern Gaza for the next phase of its ongoing war, the senior Hamas official Saleh al-Arouri was killed in a targeted assassination in Beirut. While Israel did not claim responsibility, Hezbollah held it directly accountable for the killing. The incident marks a significant escalation, as it represents Israel’s deepest incursion into Lebanese territory since 8 October and its most significant attack since July 2006. Moreover, it breaches established red lines and rules of engagement by expanding the war theatre to Beirut, disregarding a warning issued by Hezbollah leader Hassan Nasrallah in August, when he cautioned Israel against engaging in assassinations on Lebanese soil.

Historically, Hezbollah has preferred to gradually build up its military capabilities over the long term rather than immediately responding to attacks in kind. But the current war, and this recent act of escalation, will compel the movement to act swiftly to deter further Israeli aggression. In its eyes, a clear response will be the only way to restore equilibrium.

Arouri was a high-value target and his killing is a huge blow to Hamas given his longstanding role as a negotiator, including his involvement in the current prisoner exchange talks with Israel, and in ongoing efforts for cooperation between Hamas and the rival Fatah movement. He was also one of the architects of the rapprochement between Hamas on the one hand, and Iran, Hezbollah and Syria on the other, after ties had deteriorated in the wake of the Syrian war. In that sense, his assassination is a major loss for Hezbollah as well. By taking out such a high-value target, Israel is hoping to present this as a symbolic victory to its public after failing to capture or kill any senior officials in Gaza.

One of Hezbollah’s primary concerns is the further targeting of Palestinian officials in Lebanon. Israel’s shift in strategy to a lower-intensity “phase 3” – prompted by US pressure – has led to the redirection of some of its efforts toward operations that neutralise senior Hamas and Islamic Jihad operatives abroad. According to leaked recordings, the head of Shin Bet declared Israel’s intent to kill Hamas leaders “in every location”, no matter how many years it takes. US officials have lent their support to this policy, and the US national security council spokesperson, John Kirby, gave the strategy legitimacy by comparing it to the US’s own war on terror and campaign of exterritorial law enforcement. Hezbollah is in all likelihood concerned that a failure to respond decisively will invite Israel to go on an extrajudicial killing spree in Beirut – not just against Hamas but also eventually against its own officials. An even greater concern is that Israel is seeking to provoke Hezbollah into a full-scale war that would involve the US as a co-belligerent.

What is clear for now is that one of the aims of Israel’s attack was to send Hezbollah a message that Lebanon will no longer be a safe haven for Hamas. In all likelihood, Hezbollah’s response will attempt to ensure that the balance of deterrence is re-established without provoking or embarrassing Israel. This would require a carefully measured retaliation that simultaneously signifies an escalation in terms of scope and intensity, but falls short of all-out war. Right before announcing that Arouri’s killing would not go unpunished, Nasrallah threatened Israel that “a war with us will be very, very, very costly”. This suggests that the movement is preparing a major retaliation that could prompt Israel to escalate further if it misreads Hezbollah’s intentions. But there is also a danger for the Lebanese paramilitary group that Israel might misinterpret a sub-threshold response as a sign that it wants to avoid war at all costs. Hezbollah is keen to avoid an all-out war – but it is ready for one.

Hezbollah would not have taken the initiative on 8 October and embarked on its “solidarity with Palestine” military campaign had it not been ready for the possibility that its moderate-intensity conflict with Israel could metastasise into a high-intensity conventional one. It has similarly thumbed its nose at Israeli threats to attack Lebanon if Hezbollah doesn’t withdraw its forces from the border area and end its cross-border strikes.

The movement is confident not only that it can withstand Israeli aggression, regardless of the costs in terms of casualties and infrastructure to Lebanon, but also that it can wreak equal destruction on Israel. Given that Hezbollah is closer to a conventional army than a guerrilla group, it possesses capabilities that would enable it to inflict unprecedented harm on Israel. Unlike Hamas, Hezbollah’s vast arsenal of sophisticated weapons, including long-range and guided missiles, could paralyse civilian life across Israel and cause much devastation in an upcoming war. Over and above this, Hezbollah is now a regional power in its own right and the bedrock of the “resistance axis”, an alliance led by Iran that includes Syria and Yemen’s Ansarullah, as well as Palestinian groups such as Hamas and the Islamic Resistance in Iraq. All of these actors are already involved in this stage of the conflict. Nasrallah made a threat in 2017 that “hundreds of thousands” of fighters from these allied countries would expand and deepen their involvement in the “great war” against Israel should a second front with Lebanon be opened.

Hezbollah’s ideal scenario is to return to the post-8 October rules of engagement, a period defined by tit-for-tat skirmishes along the Israel-Lebanon border, which would require that Israel absorb its response and de-escalate. Beyond that, its ultimate objective is for a ceasefire to take hold. Both of these aims depend on whether or not Israel, which is incapable of confronting Hezbollah on its own, is seeking to drag the US into a full-blown regional war. Should that be the case, the US remains the linchpin that will determine if and how this war will escalate.