The supreme leader of Iran for 37 years, Ayatollah Ali Khamenei, was killed on Saturday by US and Israeli strikes.
When the news broke there were jubilant celebrations in Iran and across the Iranian diaspora.
Yet for other Iranians, and Shia Muslims elsewhere, it triggered grief and anger.
A small number of Shia mosques in Australia have planned to host memorial services for Khamenei, sparking condemnation from members of the Iranian diaspora community and politicians.
So, what is Shia Islam?
How does it shape politics in the Middle East?
And why would Shia Muslims around the world be mourning the death of an Iranian leader?
Who are Shias?
Shiites are a minority sect of Islam estimated to account for around 15 per cent of Muslims worldwide.
The vast majority of Muslims are Sunni.
"Shia identity is rooted in victimhood over the killing of Husayn, the Prophet Mohammed's grandson, in the seventh century, and a long history of marginalisation by the Sunni majority," explains a 2023 report by the Council on Foreign Relations.
While the Quran and other religious texts are central to both sects, they differ in their interpretations of Islamic history, cultural practices and understanding of religious authority.
In simple terms, Sunni Islam is decentralised and akin to Protestant strains of Christianity.
Shiism has a hierarchical structure of clergy more comparable to that of the Catholic Church.
While there are a diversity of traditions within Shia Islam, senior religious figures such as Khamenei are influential even outside Iran.
What have global responses been to Khamenei's death?
Ayatollah Khamenei's death was a historic moment for Iranians and Shiites from Tehran to Sydney.
Iranian authorities declared him a martyr and announced 40 days of mourning.
The Islamic Revolutionary Guards Corps threatened its "most intense offensive operation" ever in response to the killing.
Scenes of grief were also seen across the Middle East and Asia in countries with large Shia populations, from Lebanon to Pakistan.
Indian Shias in Delhi and Indian-controlled Kashmir held protests against the US and Iranian strikes.
Even in Indonesia — which is overwhelmingly Sunni and where Shias face persecution — members of the minority community left tributes outside the Iranian embassy.
In Australia, five Shia mosques and Islamic centres drew criticism for holding public memorials and prayer sessions to mourn the ayatollah.
Shia National Network of Australia secretary Syed Zawar Shah said ayatollah meant a religious person who had "attained knowledge of Shia theology and jurisprudence to a required standard".
"People liked him irrespective of their countries and nationalities," he said.
"Thus they were protesting and mourning not for political reasons but for the religious reasons."
Why would Shias in Australia mourn Khamenei?
Senior government figures, including Prime Minister Anthony Albanese, have slammed vigils for Khamenei as inappropriate.
The Shia Muslim Council of Australia, a peak body, said Khamenei's death was a "religious and communal loss".
"Reducing his death to celebration alone erases the reality that millions are grieving," they said.
"It dismisses the spiritual dimension of his leadership and the sincerity of those who feel this loss deeply.
"At a time when the Muslim community is already carrying profound anguish over the humanitarian catastrophe and documented human rights violations in Gaza and elsewhere in the region, this moment compounds an already heavy burden."
Mr Shah said those issuing condemnations misunderstood the purpose of Shia commemorative events.
"What we do in such events is recite the Quran and bless the souls of the departed ones," he said.
"I think this is common in the people of all faiths to ask God for the forgiveness of the departed souls."
But he said political perspectives on the Iranian regime in the Shia community were mixed.
Deakin University chair in global Islamic politics Greg Barton emphasised it was only five out of some 80 Shia mosques and centres in Australia that held commemorative events.
And he suggested the Iranian embassy could be pressuring Iranian religious groups in Australia to do the vigils.
"The Islamic Revolutionary Guards Corps runs not just a police state in Iran but to the best of their abilities, operates out of embassies and consulates to surveil the diaspora population," Professor Barton said.
"Some members of the Australian Shia community genuinely retain respect for a Shia leader like Khamenei, who they may dislike but regard as deserving of respect — particularly in death.
"Others may go along with expressions of respect because of fear of persecution of their family back in Iran."
Australia's domestic spy agency ASIO has accused Iran of foreign interference in recent years, including the intimidation of Iranian Australian activists.
Mr Albanese cited the overseas activities of Iranian security forces while expressing support for US and Israeli strikes against Iran.
"This is a regime which has engaged in international terrorism support, including of course here in Australia with at least two antisemitic attacks," he told 7.30 on Monday.
The Iranian embassy did not respond to the ABC's request for comment.
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How does the sectarian divide shape Middle East politics?
A major fault line in the politics of the Middle East is the schism between Sunni and Shia sects of Islam.
Iran is home to many Shiite holy sites and is a destination of pilgrimage for Shias around the world.
Since the Islamic Revolution of 1979, the theocratic Iranian government has leveraged this religious significance for political aims.
In contestation with Israel and its Sunni arch rival Saudi Arabia, Iran has projected power across the Middle East where there are large Shia populations such as in Iraq, Syria and Lebanon.
It has funded and armed Shia militia groups such as Hezbollah in Lebanon and the Houthis in Yemen.
Iran on the weekend launched air strikes against primarily Sunni Arab nations such as Saudi Arabia, the United Arab Emirates and Oman.
It also struck Bahrain, which is Shia-majority but ruled by a Sunni royal family.
Importantly, these Gulf states are home to US military bases.
Are you impacted by the war in the Middle East?
