WASHINGTON: The 36-year rule of Ayatollah Ali Khamenei built Iran into a powerful anti-US force and spread its military sway across the Middle East.

He was martyred on Saturday, aged 86, Iranian state media announced, in air strikes by Israel and the US that pulverised his central Tehran compound, after decades of efforts to resolve the dispute over Iran’s nuclear programme diplomatically failed.

At first dismissed as weak and indecisive, Khamenei seemed an unlikely choice for supreme leader after the death of the charismatic Ayatollah Ruhollah Khomeini, who founded the Islamic Republic of Iran. But Khamenei’s rise to the pinnacle of the country’s power structure afforded him a tight grip over the nation’s affairs.

Khamenei went from “a weak president to an initially weak supreme leader to one of the five most powerful Iranians of the last 100 years”, Karim Sadjadpour at the Carnegie Endowment for International Peace told Reuters.

The ayatollah criticised Washington throughout his rule, continuing to deploy barbs after the start of Donald Trump’s second term as US president in 2025.

As a new wave of protests spread through Iran and as Trump threatened to intervene, Khamenei vowed in January that the country would not “yield to the enemy”.

The comment was typical of the ferociously anti-Western Khamenei, in office since 1989.

Final authority in Iran’s complex system

Khamenei long denied that Iran’s nuclear programme was aimed at producing an atomic weapon, as the West contended. In 2015, he cautiously supported a nuclear deal between world powers and the government of pragmatist President Hassan Rouhani that curbed the country’s nuclear programme in return for sanctions relief. The hard-won accord resulted in a partial lifting of Iran’s economic and political isolation.

But Khamenei’s hostility toward the US was undimmed, intensifying in 2018 when Trump’s first administration withdrew from the nuclear agreement and reimposed sanctions to choke Iran’s oil and shipping industries.

Following the US withdrawal, Khamenei sided with hardline supporters who criticised Rouhani’s policy of appeasement towards the West.

As Trump pressed Iran to agree to a new nuclear deal in 2025, Khamenei condemned “the rude and arrogant leaders of America”. “Who are you to decide whether Iran should have enrichment?” he asked.

Khamenei often denounced “the Great Satan” in speeches, reassuring hardliners for whom anti-US sentiment was at the heart of the 1979 revolution, which forced the last shah of Iran into exile.

Iran saw major student-led protests in 1999 and 2002. But Khamenei’s authority was put to the test more profoundly in 2009, when the contested results of a presidential election that he had validated ignited violent street unrest, stoking a crisis of legitimacy that lingered until his death.

In 2022, Khamenei cracked down on protesters enraged by the death of Iranian-Kurdish woman Mahsa Amini, 22, who died in the custody of morality police in September of that year.

As supreme leader, he inherited enormous powers, including command of the armed forces and the authority to appoint many senior figures, among them the heads of the judiciary, security agencies and state radio and television.

He appointed allies as commanders of the elite Revolutionary Guards.

As the final authority in Iran’s complex system of clerical rule and democracy, Khamenei long sought to ensure that no group, even among his closest allies, mustered enough power to challenge him and his anti-US stance.

An unlikely rise to power

Ali Khamenei was born in Mashhad, northeast Iran, in April 1939. His religious commitment was clear when he became a cleric at the age of 11. He studied in Iraq and in Qom, Iran’s religious capital.

His father, a religious scholar of ethnic Azeri descent, was a traditionalist cleric opposed to mixing religion and politics. In contrast, his son embraced the Islamist revolutionary cause.

“He (Khamenei’s father) came across as a modernist or progressive cleric,” said Mahmoud Moradkhani, a nephew. Unlike his son, “he was not a part of the fundamentalists”, Moradkhani said.

In 1963, Khamenei served the first of many terms in prison when at 24 he was detained for political activities. Later that year he was imprisoned for 10 days in Mashhad, where he underwent severe torture, according to his official biography.

After the Shah’s fall, Khamenei took up several posts in the Islamic Republic. As deputy minister of defence, he became close to the military and was a key figure in the 1980-88 war with neighbouring Iraq, which claimed an estimated total of one million lives.

A skilled orator, he was appointed by Khomeini as a Friday prayer leader in Tehran.

There were questions about his rapid, unprecedented rise. He won the presidency with Khomeini’s support — the first cleric in the post — and was a surprise choice as Khomeini’s successor, given that he lacked both Khomeini’s popular appeal and superior clerical credentials.

Expanding Iran’s influence

He presided over a vast financial empire through Setad, an organisation founded by Khomeini but expanded hugely under Khamenei, with assets worth tens of billions of dollars.

Khamenei expanded Iranian influence in the region. He spent billions over four decades on his allies.

But in 2024, Khamenei saw these alliances unravel, and Iran’s regional influence shrivel, with the ousting of Syrian President Bashar al-Assad and a series of defeats inflicted by Israel on Hezbollah in Lebanon and on Hamas in Gaza, including the killing of their leaders.

Under Khamenei’s rule, Iran and Israel fought a shadow war for years, with Israel assassinating Tehran’s nuclear scientists and Revolutionary Guard commanders.

It exploded into the open during Israel’s war on Hamas in Gaza from 2023. In April 2024, Iran fired hundreds of missiles and drones at Israel after it bombed Tehran’s embassy compound in Damascus. Israel struck Iranian soil in response.

But that was only a prelude to June 2025, when Israel’s military unleashed hundreds of fighter jets to strike Iranian nuclear and military targets as well as senior personnel. The surprise attack provoked a barrage of missiles in both directions, transforming simmering conflict into all-out war. The US joined the air offensive on Iran, which lasted 12 days.

The US and Israel had warned they would strike again if Iran pressed ahead with its nuclear and ballistic missile programmes and, on Saturday, they launched the most ambitious attack on Iranian targets in decades.

Negotiations between US and Iranian officials took place as recently as Thursday, but senior US officials said that Iran had not been willing to give up its ability to enrich uranium, which the Iranians argued they wanted for nuclear energy but US officials said would enable the country to build a nuclear bomb.

On the diplomatic front, Khamenei rejected any normalisation of ties with the United States. He argued that Washington had backed hardline groups like Daesh to inflame a sectarian war in the region.

Like all Iranian officials, Khamenei denied any intent to develop nuclear weapons and went so far as to issue an Islamic ruling, or fatwa, in the mid-1990s on “production and usage” of nuclear weapons, saying: “It is against our Islamic thoughts.”

The late ayatollah leaves an Islamic Republic wrestling with uncertainty amid the attacks from Israel and the United States, as well as growing dissent at home, especially among younger generations.