The Israeli air strike, which killed Iran's security chief, Ali Larijani, has removed one of the Islamic Republic's most experienced and influential policymakers at a critical moment.

Larijani was not a military commander, but he was a central figure in shaping Iran's strategic decisions.

As secretary of the Supreme National Security Council, he sat at the heart of decision-making on war, diplomacy, and national security.

His voice carried weight across the system, particularly in managing Iran's confrontation with the United States and Israel.

After the killing of Supreme Leader Ali Khamenei on 28 February, Larijani struck a defiant tone, signalling that Iran was prepared for a long conflict.

His death, now confirmed by state media, comes amid a broader campaign in which several senior Iranian officials and commanders have been killed within a matter of weeks. This pattern suggests a sustained effort to weaken Iran's leadership structure during wartime.

Despite his hardline stance against the West, Larijani was often described inside Iran as a pragmatist. He combined ideological loyalty with a technocratic approach, favouring calculated strategy over rhetoric.

He remained deeply sceptical of engagement with Western powers, but he was also involved in key diplomatic efforts, including serving as an envoy to Iran on its long-term co-operation agreement with China.

At the time of his death, Larijani was overseeing three major crises.

The first was the war itself. He argued that Iran should prepare for a prolonged struggle and expand the conflict across the region and beyond, including the closure of the Strait of Hormuz.

The second was a wave of domestic unrest, which began with economic grievances but quickly turned into wider protests seeking to topple the Islamic Republic. These were met with a crackdown that killed many thousands of protesters across the country.

The third was Iran's nuclear programme and stalled indirect negotiations with Washington, both of which had already been disrupted by military strikes.

His removal leaves these issues unresolved and transfers them to an as-yet-unknown successor, who faces an extremely fragile situation. While Iran has shown resilience, partly by disrupting global energy markets, its airspace remains open to continued strikes. Any new senior figure will face immediate risk of being targeted.

This may shift power further towards the military. Recent remarks by President Masoud Pezeshkian suggest that armed forces units have effectively been given broad authority to act if senior leadership is incapacitated. In practice, that could mean decisions being taken more quickly, but with less central coordination.

There are also signs that the leadership is struggling to manage succession. Iran has delayed public announcements and kept some figures, including the new supreme leader, Mojtaba Khamenei, largely out of sight. Whether this is for security reasons or due to internal uncertainty is unclear.

In the short term, the likely outcome is a more volatile situation: a harder military posture in the war and harsher repression at home.

Iranian army chief Amir Hatami has also threatened to launch a "decisive" retaliation for Larijani's death.

Over time, however, a system that continues to lose senior figures may find it increasingly difficult to function effectively, especially in a country of more than 90 million people.

The impact of Larijani's death, then, is not just about the loss of a single official. It deepens a leadership crisis that could affect both the course of the war and the stability of the Iranian state itself.