Hezbollah was in disarray on Thursday after a second wave of deadly explosions swept through its strongholds across Lebanon, putting pressure on its leader to exact revenge for the operation it blames on Israel.
The attack killed 32 people in two days, including two children, and wounded more than 3,000 others, according to Lebanese health ministry figures.
Israel has not commented on the unprecedented operation that saw Hezbollah operatives' walkie-talkies and pagers exploding in supermarkets, at funerals and on streets.
But its defence minister, Yoav Gallant, said on Wednesday, in reference to Israel's border with Lebanon: "The centre of gravity is moving northward."
"We are at the start of a new phase in the war", he said.
Hezbollah is an ally of Palestinian militant group Hamas, which has been fighting a war in Gaza since its October 7 attack on Israel.
For nearly a year, the focus of Israel's firepower has been on Gaza, which is ruled by Hamas.
But its troops have also been engaged in near-daily clashes with Hezbollah militants along its northern border, killing hundreds in Lebanon, most of them fighters, and dozens more in Israel.
The exchanges of fire have also forced tens of thousands of people on both sides of the border to flee their homes.
Gallant said earlier this month that Hamas as a military formation "no longer exists".
Reeling from the operation that targeted its communication system, Iran-backed militant group Hezbollah said Israel was "fully responsible for this criminal aggression" and vowed revenge.
Hezbollah on Thursday said 20 of its members had been killed, with a source close to the group saying they had died when their walkie-talkies had exploded a day earlier.
At 5:00 pm (1400 GMT) on Thursday, Hezbollah leader Hassan Nasrallah will give a previously unscheduled televised speech that will be watched closely by both his supporters and his enemies for any signals of what shape a response might take.
Lebanese Foreign Minister Abdallah Bou Habib said the "blatant assault on Lebanon's sovereignty and security" was a dangerous development that could "signal a wider war".
Iran's envoy to the UN said the country "reserves the right to take retaliatory measures" after its ambassador in Beirut was wounded in the blasts.
"We don't believe that the way to solve where we're at in this crisis is by additional military operations at all," US National Security Council spokesman John Kirby told reporters.
The October 7 attacks that sparked the war in Gaza resulted in the deaths of 1,205 people, mostly civilians, on the Israeli side, according to an AFP tally based on official Israeli figures that include hostages killed in captivity.
Out of 251 hostages seized by militants, 97 are still held in Gaza, including 33 the Israeli military says are dead.
Israel's retaliatory military offensive has killed at least 41,272 people in Gaza, most of them civilians, according to data provided by the Hamas-run territory's health ministry. The UN has acknowledged these figures as reliable.
In Gaza on Wednesday, the civil defence agency said an Israeli strike on a school-turned-shelter killed five people, while the Israeli military said it targeted Hamas militants.
In Lebanon, the influx of so many casualties following the blasts overwhelmed medics.
At a Beirut hospital, doctor Joelle Khadra said "the injuries were mainly to the eyes and hands, with finger amputations, shrapnel in the eyes -- some people lost their sight."
A doctor at another hospital in the Lebanese capital said he had worked through the night and that the injuries were "out of this world -- never seen anything like it".
Analysts said operatives had likely planted explosives on the pagers before they were delivered to Hezbollah.
The preliminary findings of a Lebanese investigation found the pagers had been booby-trapped, a security official said.
"Data indicates the devices were pre-programmed to detonate and contained explosive materials planted next to the battery," the official said, requesting anonymity to discuss sensitive matters.
A source close to Hezbollah, asking not to be identified, said the pagers were "recently imported" and appeared to have been "sabotaged at source".
After The New York Times reported that the pagers that exploded on Wednesday had been ordered from Taiwanese manufacturer Gold Apollo, the company said they had been produced by its Hungarian partner BAC Consulting KFT.
A government spokesman in Budapest said the company was "a trading intermediary, with no manufacturing or operational site in Hungary".
Japanese firm Icom said that it had stopped producing the model of radios reportedly used in Wednesday's blasts in Lebanon around 10 years ago.
