The assassination of Iran’s Supreme Leader Ayatollah Ali Khamenei has plunged the Islamic Republic into its most perilous crisis since the 1979 revolution - confronting it with war on its own territory, an unresolved succession, and mounting internal strain.

Despite the shock of Khamenei’s killing, five regional officials and analysts cautioned against assuming a rapid collapse. Iran’s political order, they said, was deliberately constructed to avoid reliance on a single leader, dispersing authority across clerical institutions, the security apparatus and power networks.

“The Iranian system is bigger than one man - removing Khamenei could harden the regime rather than weaken it,” said Danny Citrinowicz of the Atlantic Council.

“Iran was built to survive the loss of a leader,” added Ali Hashem, a research affiliate at Royal Holloway, University of London. “The danger is not a vacuum. It’s whether war and pressure push the system past the point where that resilience holds.”

At the centre of that resilience is the elite Islamic Revolutionary Guards Corps (IRGC), long regarded as Iran’s true centre of gravity. The balance of power now hinges on whether the Guards emerge weakened by battlefield losses and internal frictions - or more entrenched, closing ranks around a harder, more security-driven approach to governance.

“The real question is whether Khamenei’s death takes the air out of the IRGC - the force that actually runs Iran - or whether they close ranks and harden,” said Alex Vatanka, a senior fellow at the Middle East Institute. “If rank-and-file officials decide there is no future here, I’m not sure even the Guards can keep the regime together.”

Regional officials say the Guards are unlikely to transform ideologically because their identity and mandate are rooted in protecting the revolution. But they are capable of tactical evolution if the system requires it.

“They may evolve into a less hardline force...there are pragmatic mid-level members open to reducing tensions with the United States if necessary for the system’s survival,” said one regional official. That conditional pragmatism makes the IRGC both the system’s shield and its key barometer.

Regime change?

Jonathan Panikoff, a former US deputy national intelligence officer for the Near East, said Washington and Israel appear to be pursuing a strategy aimed not only at degrading Iran’s military response capabilities, but at destabilising the regime itself by removing its senior leadership and testing the loyalty of the rank and file.

The success of that approach, he said, would ultimately depend on whether security forces stand aside or defect if public unrest resurfaces.

In the immediate aftermath, officials say Tehran’s overriding priority is to project continuity. Operationally, Iran’s command structure continues to function, though under heavy pressure. Missile forces, air defences and top commanders have been hit, but the system has so far absorbed the blows.

Iran now faces three intersecting tests, officials say: whether its security state can hold under fire; whether its embattled elite can agree on a successor or pivot to a new governing formula; and whether a shaken public pushes the crisis toward a deeper political rupture.

Veteran Iranian politician Ali Larijani, secretary of Iran’s Supreme National Security Council, announced on Sunday that a temporary leadership council would oversee the transitional period after Khamenei’s death.

Figures such as Larijani and Mohammad Baqer Qalibaf, the parliament speaker, are seen as potential bridge figures in such a phase, reflecting a security-oriented but pragmatic balancing approach.

Politically, Iran faces a succession process it has navigated only once before - and then under far more stable conditions. The constitution assigns the task to the Assembly of Experts, an 88-member clerical body, but analysts say wartime pressures could push the process toward a more improvised outcome - either a quickly appointed successor or a temporary collective leadership centered on the security establishment.

They said Khamenei has sought to shape that outcome before his death. Following a 12-day war with Israel in June last year that targeted him and his inner circle, he nominated preferred successors and ensured key military posts were filled with backup commanders.

The candidates he favoured included judiciary chief Gholam-Hossein Mohseni-Eje’i and Hassan Khomeini, a moderate cleric and grandson of the Islamic Republic’s late founder.

But officials say the clerical body may delay the selection of a successor to Khamenei for fear he will be killed.

Far from over?

Externally, Israel is signalling the campaign is far from over. Two sources briefed on the operation said Israel intends to keep striking political and security institutions linked to Iran’s ruling establishment, as well as ballistic missile and launcher systems, in an effort to weaken the state and create conditions for regime change.

One source said Israel wants the campaign to continue at least until Iran’s missile capabilities are destroyed, but fears it could be cut short if Washington reaches an agreement with Tehran.

“The objective is very clear: to remove an existential threat to the State of Israel,” Israeli Foreign Ministry spokesperson Oren Marmorstein told Reuters in Tel Aviv. “That threat is the Iranian regime. We have no quarrel with the Iranian people.”

A senior official with direct knowledge of joint Israeli-US military planning said it was too early to predict what political order might emerge in Iran, noting that the campaign was still in its early stages and outcomes would depend on developments on the ground.

Iranians must take their destiny into their own hands, the official said, adding that this might be easier once the US and Israel have achieved “air supremacy” over Iran.

Maintaining the tempo and intensity of strikes was seen as critical to exploiting fissures inside Iran and the IRGC following the killing of senior leaders, the official added, declining to elaborate on what a breakdown in command could look like.

The conflict has also opened new risks.

With foreign militaries operating over Iranian airspace and the state’s coercive capacity under strain, analysts say unrest could intensify if large-scale anti-government protests re-emerge, raising the prospect of defections within the security forces and giving prominence to civilian figures calling for change.