Senior clerics in Iran are accelerating the hunt for a successor to Iran's Supreme leader Ayatollah Ali Khamenei following increased Israeli strikes.
A three-man committee from a top clerical body, appointed by Mr Khamenei himself two years ago to identify his replacement, has accelerated its planning in recent days since Israel attacked Iran and threatened to assassinate the veteran leader.
Mr Khamenei, 86, is being briefed on talks and has gone into hiding with his family and is being guarded by the Vali-ye Amr special forces unit of the Revolutionary Guards, a top security official said.
The ruling establishment will immediately seek to name a successor to Mr Khamenei if he is killed.
A new leader will still be chosen for his devotion to the revolutionary precepts of the Islamic Republic's late founder Ayatollah Ruhollah Khomeini, who is close to Mr Khamenei's office and privy to the talks.
At the same time, the top echelon of power is also considering which candidate might present a more moderate face to ward off foreign attacks and internal revolts.
Who are the front runners in the race for Supreme leader?
Two front runners have emerged in the succession discussions, including the Ayatollah's 56-year-old son Mojtaba Khamenei, long seen as a continuity choice, and a new contender, Hassan Khomeini, who is a grandson of the father of the Islamic revolution.
Hassan Khomeini, a close ally of the reformist faction that favours the easing of social and political restrictions, commands respect among senior clerics and the Revolutionary Guards because of his lineage.
"I once again humbly express that this small and insignificant servant of the Iranian people stands ready to proudly be present on any front or scene you deem necessary," Hassan Khomeini said.
He has come into the frame as a serious candidate this month amid the conflict with Israel and America because he could represent a more conciliatory choice internationally and domestically than Mojtaba Khamenei, sources said.
By contrast, Mr Khamenei aligns closely to his father's hardline policies, they added.
However, with the military conflict continuing, it remains unclear whether any new leader could be chosen easily or installed securely or if he could assume the level of authority enjoyed by the Ayatollah.
Israeli strikes have also killed several of Iran's top Revolutionary Guards commanders, potentially complicating a handover of power as the elite military force has long played a central role in enforcing the supreme leader's rule.
The Ayatollah's office and the Assembly of Experts, the clerical body from which the succession committee was drawn, were not available to comment.
Planning for an eventual handover was already in the works because of Mr Khamenei's age and the longstanding health concerns of a leader who has dominated all aspects of Iranian politics for decades, the sources said.
The urgency of the task was underlined in September when Israel killed Hezbollah leader Sayyed Hassan Nasrallah, a close ally of the Ayatollah's.
The planning then accelerated significantly this month following the Israeli attacks on nuclear sites, which were followed by the American attacks at the weekend.
"We know exactly where the so-called 'Supreme Leader' is hiding," US President Donald Trump warned on social media last week, calling for Tehran's unconditional surrender. "He is an easy target."
Mr Khamenei hasn't publicly expressed any preference for his successor.
Sources say he had repeatedly opposed the idea of his son taking over, in succession discussions in the past, concerned about any suggestion of Iran returning to the kind of hereditary rule that ended with the ousting of the shah in 1979.
What is a supreme leader?
The role of Supreme leader was created after the revolution and then enshrined in the constitution giving a top cleric ultimate authority in guiding the elected president and parliament.
Officially, the leader is named by the Assembly of Experts, made up of 88 senior clerics.
They are chosen through a national election in which a hardline watchdog body aligned with Mr Khamenei approves all the candidates.
"Whether the Islamic Republic survives or not, it will be a very different one, because the context in which it has existed has fundamentally changed," said London-based Iranian political analyst Hossein Rassam.
He added that Hassan Khomeini could "fit the bill" for a leader to take Iran in a new direction.
"The regime has to opt for someone who'll facilitate slow transition," Mr Rassam said.
Hassan Khomeini
Hassan Khomeini's close links to the reformist faction of Iranian politics, which pursued an ultimately unsuccessful policy of opening Iran to the outside world in the 1990s, saw hardline officials bar him from running as a member of senior clerical body the Assembly of Experts in 2016.
The succession planners are aware that Hassan Khomeini is likely to be more palatable to the Iranian population than a hardliner, five insiders have said.
Last year he warned of a "crisis of rising popular dissatisfaction" among Iranians due to poverty and deprivation.
Mojtaba Khamenei
By contrast, Mojtaba Khamenei's views echo those of his father on every major topic from cracking down on opponents to taking a hardline with foreign foes.
A mid-ranking cleric who teaches theology at a religious seminary in the city Qom, the centre of Iranian religious life, Mr Mojtaba has never held a formal position in the Islamic Republic, though exercises influence behind the scenes as the gatekeeper to his father.
The US Treasury Department imposed sanctions on Mr Mojtaba in 2019.
The department had said he represented the Supreme leader in "an official capacity despite never being elected or appointed to a government position" aside from working his father's office.
Other candidates
Several of the candidates long seen as possible successors to Mr Khamenei have already died.
Former president Hashemi Rafsanjani died in 2017, while former judiciary chief Mahmoud Hashemi Shahroudi died in 2018.
Former President Ebrahim Raisi was killed in a helicopter crash in 2023.
Another senior cleric, Sadegh Amoli Larijani, has been sidelined.
Others, such as the Assembly of Experts member Ayatollah Alireza Arafi, are still in contention but have fallen behind Mojtaba Khamenei and Hassan Khomeini, the five sources said.
Beyond the most likely candidates, it's also possible that a less prominent cleric could be chosen as a pawn of Revolutionary Guards, said Ali Vaez, Iran project director at the International Crisis Group think-tank.
"It is possible that they would put forward a candidate that no one has ever heard of and would not really hold the same levers of power that Ayatollah Khamenei has held now for more than 30 years," he said.
After the death of the Islamic Republic's founder Ruhollah Khomeini in 1989, Mr Khamenei was publicly hailed as his predecessor's choice.
Although he had already served as president, Mr Khamenei was only a mid-ranking cleric and was initially dismissed by influential clerics as weak and an unlikely successor to his charismatic predecessor.
However, he steadily tightened his grip to become Iran's unquestioned decision-maker, relying on the Revolutionary Guards as he outmanoeuvred rivals and crushed bouts of popular unrest.
