Israel on alert as Hezbollah leader vows retribution for Hamas leader's death

Israel has insisted the killing of a top Hamas leader in Beirut was not an attack on Lebanon.

However, an Israeli spokesman said the attack that killed Saleh al-Arouri was a "surgical strike against the Hamas leadership".

Hamas denounced the killing as a "terrorist act", while Hamas ally Hezbollah said it was an assault on Lebanese sovereignty.

Al-Arouri is the most senior Hamas figure killed since the Israel-Hamas war began in October, and his death's implications for the war remain unclear.

Israel has killed several top Hamas leaders over the years, only to see them quickly replaced. But the strike in Hezbollah's southern Beirut stronghold could inflame the low-intensity fighting already unfolding along the Lebanon border, which theoretically could boil over into all-out war.

Hezbollah said its fighters attacked two Israeli border posts on Wednesday using “suitable weapons” and scoring “direct hits." The two sides also exchanged fire overnight, but Hezbollah did not directly link its actions to Arouri's killing. There was no immediate comment from the Israeli military.

Arouri was the deputy of Hamas’ supreme political leader, Ismail Haniyeh, and headed the group’s presence in the Israeli-occupied West Bank. He was also a key liaison with Hezbollah. The US State Department had listed him as a terrorist and offered a $5 million  (€4.53 million) reward for information about him.

Haniyeh said Hamas was “more powerful and determined” following the attack, which killed six other members of the group, including two military commanders. “They left behind them strong men who will carry the banner after them,” he said of those killed.

Israeli officials have not commented on the strike that killed Arouri, but Rear Admiral Daniel Hagari, an Israeli military spokesman, said “we are on high readiness for any scenario.”

Hezbollah called the strike “a serious attack on Lebanon, its people, its security, sovereignty and resistance.”

“We affirm that this crime will never pass without response and punishment,” it said.

However, much depends on the response of Hassan Nasrallah, who has led Hezbollah since an Israeli strike killed his predecessor in 1992. He has previously vowed to retaliate against any Israeli targeting of allied militant leaders in Lebanon, and was expected to deliver a speech this evening.

Hezbollah and the Israeli military have been exchanging fire almost daily over the Israeli-Lebanese border since the war in Gaza began, but Nasrallah has appeared reluctant to escalate it further, perhaps fearing a repeat of the month-long 2006 war in which Israel heavily bombed Beirut and southern Lebanon.

Prime Minister Benjamin Netanyahu and other Israeli officials have repeatedly threatened to kill Hamas leaders wherever they are. The group's 7 October attack from Gaza into southern Israel killed around 1,200 people, and some 240 others were taken hostage.

Israel claims to have killed a number of mid-level Hamas leaders in Gaza, but this would be the first time since the war that it has reached into another country to target the group's top leaders, many of whom live in exile around the region.

For now, the focus of the war remains on Gaza itself. Israeli Defense Minister Yoav Gallant insists Israel is seeking a “clear victory” over Hamas, which has ruled the territory since 2007.

Israel's air, ground and sea assault on Gaza has killed more than 22,300 people, two-thirds of them women and children, according to the Health Ministry in the Hamas-ruled territory. The count does not differentiate between civilians and combatants.