Iran's 86-year-old Supreme Leader Ayatollah Ali Khamenei cuts an increasingly lonely figure.
One of those sources, who regularly attends meetings with Khamenei, described the risk of miscalculation to Iran on issues of defence and internal stability as "extremely dangerous".
Several senior military commanders have been killed since Friday including Khamenei's main advisers from the Revolutionary Guards, Iran's elite military force: the Guards' overall commander Hossein Salami, its aerospace chief Amir Ali Hajizadeh who headed Iran's ballistic missile program and spymaster Mohammad Kazemi.
These men were part of the supreme leader's inner circle of roughly 15-20 advisers comprising Guards commanders, clerics, and politicians, according to the sources who include three people who attend or have attended meetings with the leader on major issues and two close to officials who regularly attend.
The loose group meets on an ad-hoc basis, when Khamenei's office reaches out to relevant advisers to gather at his compound in Tehran to discuss an important decision, all the people said. Members are characterised by unwavering loyalty to him and the ideology of the Islamic Republic, they added.
Khamenei, who was imprisoned before the 1979 revolution and maimed by a bomb attack before becoming leader in 1989, is profoundly committed to maintaining Iran's Islamic system of government and deeply mistrustful of the West.
Under Iran's system of government he has supreme command of the armed forces, the power to declare war, and can appoint or dismiss senior figures including military commanders and judges.
Khamenei makes the final decision on important matters, though he values advice, listens attentively to diverse viewpoints, and often seeks additional information from his counsellors, according to one source who attends meetings.
"Two things you can say about Khamenei: he is extremely stubborn but also extremely cautious. He is very cautious. That is why he has been in power for as long as he has," said Alex Vatanka, director of the Iran Program at the Middle East Institute think-tank in Washington.
"Khamenei is pretty well placed to do the basic cost-benefit analysis which really fundamentally gets to one issue more important than anything else: regime survival."
KHAMENEI'S SON AT THE FORE
The focus on survival has repeatedly been put to the test. Khamenei has deployed the Revolutionary Guards and its affiliated Basij militia to quell national protests in 1999, 2009 and 2022.
While the security forces have always been able to outlast demonstrators and restore state rule, years of Western sanctions have caused widespread economic misery that analysts say could ultimately threaten internal unrest.
The stakes could barely be higher for Khamenei who faces an escalating war with Israel, which has targeted nuclear and military sites and personnel with air attacks, drawing retaliatory Iranian missile fire.
The five people familiar with Khamenei's decision-making process stressed that other insiders who have not been targeted by Israel's strikes remain important and influential, including top advisers on political, economic and diplomatic issues.
Khamenei designates such advisers to handle issues as they arise, extending his reach directly into a wide array of institutions spanning military, security, cultural, political and economic domains, two of the sources said.
Operating this way, including in bodies nominally under the elected president, means Khamenei's office is often involved not only in the biggest questions of state but in executing even minor initiatives, according to the people with knowledge.
His son Mojtaba has grown ever more central to this process over the past 20 years, the sources said, building a role that cuts between the personalities, factions and organisations involved to coordinate on specific issues, the sources said.
A mid-ranking cleric seen by some insiders as a potential successor to his ageing father, Mojtaba has built close ties with the Guards, giving him added leverage across Iran's political and security apparatus, the people added.
Ali Asghar Hejazi, the deputy of political security affairs at Khamenei's office, has been involved in sensitive security decisions and is often described as the most powerful intelligence official in Iran, according to the sources said.
Meanwhile, the head of Khamenei's office, Mohammad Golpayegani, as well as former foreign ministers Ali Akbar Velayati and Kamal Kharazi, and ex-parliament speaker Ali Larijani, remain trusted confidants on diplomatic and domestic policies issues such as the nuclear dispute, the people said.
The loss of the Revolutionary Guards commanders nonetheless decimates the top ranks of a military organisation that Khamenei has put at the centre of power since becoming supreme leader in 1989, relying on it for both internal security and regional strategy.
While the regular army chain of command runs through the defence ministry under the elected president, the Guards answer personally to Khamenei, securing the best military equipment for their land, air and sea branches and giving their commanders a major state role.
As he faces one of the most dangerous moments in the Islamic Republic's history, Khamenei finds himself further isolated by the recent losses other key advisers in the region as Iran's "Axis of Resistance" coalition has been hammered by Israel.
Hezbollah chief Hassan Nasrallah, who was personally close to the Iranian leader, was killed by an Israeli airstrike in September last year and Syrian President Bashar al-Assad was overthrown by rebels in December.
