(REUTERS) - President Bashar al-Assad used Russian and Iranian firepower to beat back rebel forces during years of civil war but never defeated them, leaving him vulnerable when his allies were distracted by wars elsewhere and his enemies went on the march.
The rebels' lightning advance through western Syria marks one of the most serious threats to half a century of Assad family rule in Damascus, and a seismic moment for the Middle East.
Statues of Assad's father and brother were toppled in cities taken by the rebels, while pictures of him on billboards and government offices have been torn down, stamped on, burned or riddled with bullets.
The Syrian presidency issued a statement on Saturday denying Assad had left the country and saying he was carrying out his duties in Damascus.
Assad became president in 2000 after his father Hafez died, preserving the dominance of their Alawite sect in the Sunni Muslim-majority country and Syria's status as an Iranian ally hostile to Israel and the U.S.
Shaped in its early years by the Iraq war and crisis in Lebanon, his rule has been defined by the civil war which spiralled out of the 2011 Arab Spring, when Syrians demanding democracy took to the streets, to be met with deadly force.
Branded an "animal" in 2018 by U.S. President Donald Trump for using chemical weapons - an accusation he denied - Assad has outlasted many of the foreign leaders who believed his demise was imminent in the early days of the conflict, when he lost swathes of Syria to rebels.
Helped by Russian air strikes and Iranian-backed militias, he clawed back much of the lost territory during years of military offensives, including siege warfare condemned as "medieval" by U.N. investigators.
With his opponents largely confined to a corner of northwestern Syria, he presided over several years of relative calm though large parts of the country remained out of his grasp and the economy was shackled by sanctions.
He re-established ties with Arab states that once shunned him but remained a pariah to much of the world.
Assad has not delivered any public remarks since insurgents took Aleppo a week ago but said in a call with Iran's president that the escalation sought to redraw the region for Western interests, echoing his view of the revolt as a foreign-backed conspiracy.
Justifying his response to the insurgency in its early stages, Assad compared himself to a surgeon. "Do we say to him: 'your hands are covered in blood?' Or do we thank him for saving the patient?" he said in 2012.
Early in the conflict, as rebels seized town after town, he oozed confidence.
"We will hit them with an iron fist and Syria will return to how it was," Assad told soldiers after taking back the town of Maaloula in 2014.
He delivered on the first pledge, but not the second. Years later, large parts of Syria remained outside state control, cities were flattened, the death toll topped 350,000, and more than a quarter of the population had fled abroad.
RED LINES
Assad has been backed by those Syrians who believed he was saving them from hardline Sunni Islamists.
As al Qaeda-inspired insurgent groups gained prominence, this fear resonated among minorities even though the rebels went out of their way to reassure them this week that they would be protected.
Assad clung to the idea of Syria as a bastion of secular Arab nationalism even as the conflict appeared ever more sectarian. Speaking to Foreign Affairs in 2015, he said Syria's army was "made up of every colour of Syrian society".
But to his opponents, he was fuelling sectarianism.
The conflict's sectarian edge was hardened by the arrival of Iranian-backed Shi'ite fighters from across the Middle East to support Assad, and as Sunni Muslim-led states including Turkey and Qatar backed the rebels.
Assad's value to Iran was underscored by a senior Iranian official who declared in 2015 that his fate was a "red line" for Tehran.
While Iran stood by Assad, the United States failed to enforce its own "red line" - set by President Barack Obama in 2012 against the use of chemical weapons.
U.N.-backed investigations have concluded Damascus used chemical weapons.
A sarin gas attack on the rebel-held Ghouta in 2013 killed hundreds but Moscow brokered a deal for Syria's chemical weapons to be destroyed, averting a U.S. response.
Still poison gas continued to hit rebel areas, with a 2017 sarin attack prompting Trump to order a cruise missile response.
Assad has denied accusations the state was to blame.
He similarly denied the army had dropped barrel bombs packed with explosives that caused indiscriminate destruction. He appeared to make light of the accusation in a BBC interview in 2015, saying: "I haven't heard of the army using barrels, or maybe, cooking pots."
He also dismissed tens of thousands of photos showing torture of people in government custody as part of a Qatar-funded plot.
As fighting died down, Assad accused Syria's enemies of economic warfare.
But while Assad remained a pariah to the West, some Arab states which once backed his opponents began opening doors to him. A beaming Assad was greeted by leaders of the United Arab Emirates during a visit there in 2022.
EYE DOCTOR
Assad often presented himself as a humble man of the people, appearing in films driving a modest family car and in photographs with his wife visiting war veterans in their homes.
He took office in 2000 after his father's death, but had not always been destined for the presidency.
Hafez had groomed another son, Bassel, to succeed him. But when Bassel died in a 1994 car crash, Bashar was transformed from an eye doctor in London - where he studied as a postgraduate - to heir apparent.
Upon becoming president, Assad seemed to adopt liberal reforms, painted optimistically as "the Damascus spring".
He released hundreds of political prisoners, made overtures to the West, and opened the economy to private companies.
His marriage to British-born former investment banker Asma Akhras - with whom he had three children - helped foster hopes he could take Syria down a more reformist path.
High points of his early dalliance with Western leaders included attendance at a Paris summit where he was a guest of honour at the annual Bastille Day military parade.
But with the political system he inherited left intact, signs of change quickly dried up.
Dissidents were jailed and economic reforms contributed to what U.S. diplomats described, in a 2008 embassy cable released by WikiLeaks, as "parasitic" nepotism and corruption.
While the elite did well, drought drove the poor from rural areas to slums where the revolt would blaze.
Tensions built with the West after the U.S.-led invasion of Iraq in 2003 turned the Middle Eastern power balance on its head.
The assassination of Lebanon's Rafik al-Hariri in Beirut in 2005 prompted Western pressure that forced Syria's withdrawal from its neighbour. An initial international probe implicated senior Syrian and Lebanese figures in the killing.
While Syria denied involvement, former vice president Abdel-Halim Khaddam said Assad had threatened Hariri months earlier - an accusation Assad also denied.
Fifteen years later, a U.N.-backed court found a member of the Iranian-backed Hezbollah guilty of conspiring to kill Hariri. Hezbollah, an Assad ally, denied any role.
(Writing by Tom Perry, Editing by William Maclean and Giles Elgood)
