Israel's killing of Hassan Nasrallah leaves Hezbollah under huge pressure to deliver a resounding response to silence suspicions that the once seemingly invincible movement is a spent force, analysts said.
Widely seen as the most powerful man in Lebanon before his death of Friday, Nasrallah was the face of Hezbollah and Israel's arch-nemesis for more than 30 years.
His group had gained an aura of invincibility for its part in forcing Israel to withdraw troops from south Lebanon in 2000, and after waging a devastating 33-day-long war in 2006 and opening a "support front" in solidarity with Gaza since October 2023.
But Nasrallah's killing in Hezbollah's southern Beirut bastion known as Dahiyeh was the culmination of two weeks of unprecedented blows to the Iran-backed group either claimed by Israel or blamed on it.
"If, at this point, Hezbollah does not respond with a strategic strike using its arsenal of long-range, precision-guided missiles, one must assume they simply can't," said Heiko Wimmen, project director for Iraq, Syria and Lebanon at the International Crisis Group.
"Either we see an unprecedented reaction by Hezbollah... or this is total defeat."
'Deterrent equation'
Hezbollah has been the most powerful group in Lebanon for decades and the only one that has kept its arms after the end of the 1975-1990 civil war.
But after nearly a year of low-intensity cross-border fighting, Israel has shifted the focus of its operation from Gaza to Lebanon, where heavy bombing since Monday has killed hundreds of people and displaced around 118,000.
This week's air assault followed pager and walkie-talkie blasts that targeted operatives of Hezbollah, killing 39 and wounding nearly 3,000.
And in the past week, Israeli strikes on south Beirut have killed one top Hezbollah commander after the other.
For Sam Heller, an analyst with the Century Foundation, a lack of deterrence after such an important leader's killing could encourage Israel to press on even further.
In nearly a year of cross-border fighting with Israel, Hezbollah "haven't mustered the more dramatic capabilities that most of us had assumed it held in reserve", even as its foe intensified raids and conducted sophisticated operations, said Heller.
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Hezbollah's capabilities may have been "oversold" or completely obliterated by Israel, he added.
Since the 2006 war in which Hezbollah "defeated the Israelis", the group had "maintained this long-time deterrent equation", Heller said.
"Now, it seems evident Hezbollah cannot protect... itself."
'Not a one-man show'
With Lebanon's most powerful man gone and his Shiite Muslim community displaced and bereaved, its support base will expect more than just a symbolic response, analysts said.
Amal Saad, a Lebanese researcher of Hezbollah at Britain's Cardiff University, said that after the enormous blow to the now leaderless group, it would need to strike a delicate balance in choosing a response.
On the one hand, Hezbollah would seek to avoid triggering an Israeli "carpet bombing campaign against Beirut or all of Lebanon", while "at the same time raising the morale" of its supporters and fighters, she said.
Hezbollah would need to show it can protect its own people, exact revenge on Israel but also keep the peace among Lebanon's diverse religious communities.
Shiite Lebanese, which constitute the group's support base, are among the tens of thousands displaced from Lebanon's south, east and Dahiyeh by Israel's bombardment -- seeking shelter in areas where other religious communities live.
Mohanad Hage Ali, from the Carnegie Middle East Center, said Hezbollah had been "paralysed" by its recent reverses, but warned against writing the group off for good.
"It requires new leadership, a system of communications and to restore its narrative and speak to its support base," said Hage Ali.
But "it will be quite difficult to imagine the organisation wither away that quickly", he added.
Saad said that Hezbollah as an underground armed group was "designed to absorb shocks like this," citing the killing of top Hezbollah commander Imad Mughniyeh killed in a 2008 Damascus car bombing blamed on Israel.
"When the dust settles Hezbollah is not a one-man show," she said, adding that Nasrallah "is not a mythological figure. He's a person".