On 9 February, a grey-bearded and balding Syrian rebel commander wearing military dress appeared in an internet video calling for greater unity among the forces opposing President Bashar al-Assad. This was unremarkable. Syria’s rebel groups frequently issue unity statements, merge units and create umbrella groups – many of which, like the fruit of the medlar tree, turn rotten before they turn ripe.

Yet the message from Hashem al-Sheikh – a native of Aleppo imprisoned by Assad in 2005 for his jihadi beliefs and then released along with other Islamist prisoners in 2011 in an attempt to poison the nascent uprising against the regime – was hugely important in the context of the Syrian Civil War: it signalled the potential subsuming of the entire Syrian opposition to radical and reactionary forces, and to al-Qaeda in particular.

In the video, Hashem al-Sheikh announ­ced the creation of a powerful, extremist-dominated entity known as Hayat Tahrir al-Sham (HTS), or the “Committee for the Liberation of the Levant”.

One of the main groups that joined the new committee is Nur al-Din al-Zenki, a corrupt and brutal Islamist movement that was once backed by the CIA as a “vetted organisation”, though this designation was later revoked. In July last year, five months before Aleppo fell to Assad’s forces, the group’s members were filmed beheading Abdullah Tayseer in the eastern part of the city. Tayseer was a 13-year-old boy whom they accused of fighting for the regime.

Far more significant was the folding into HTS of Jabhat Fateh al-Sham (JFS), which until July was known as Jabhat al-Nusrah – and which represented al-Qaeda on the ground in Syria. JFS, comprised mainly of local fighters, had earned a degree of popular support among civilians because of its fighters’ valour and lack of corruption. The rebranding was an attempt by its leaders to recast it as a broader part of the overall uprising, and to capitalise on ordinary Syrians’ hatred of Islamic State (IS), which is widely seen as having usurped the revolution and diverted its aims.

Consequently, al-Qaeda has pursued an audacious line of messaging that seeks to portray the group in Syria as a responsible actor that follows a “middle path” between acquiescence and extremism. The corollary is clear: that it is both authentic and organic. “JFS is not a fringe group that exists on another planet,” wrote a spokesman, Mos­tafa Mahamed, shortly after it rebranded in 2016. “It is deeply embedded in society, made up from the average Syrian people.”

The creation of Hayat Tahrir al-Sham is a further coup for al-Qaeda in its quest for legitimacy within the Syrian opposition. Because Hashem al-Sheikh, the HTS leader, has never been part of JFS, the group can more credibly intertwine itself within the much wider movement. Indeed, Sheikh declared that HTS is not an umbrella organisation, and neither does it represent the continuation of any particular fighting force. It is a merger that dissolves the individual identities of its constituents, bringing them together in a wholly new entity.

Even so, its messages bear all the hallmarks of al-Qaeda. Sheikh’s first speech as leader was deeply sectarian; he declared Shias “the enemy”, cursed Alawites (the heterodox sect to which Assad belongs) and called for hostilities against the “forces of Zoroastrianism” (used in this context as a pejorative reference to Iran).

The elevation of Hashem al-Sheikh also throws a spotlight on the tensions within Ahrar al-Sham, one of the most powerful and well-armed of all the anti-Assad forces. Despite holding various extremist beliefs, the Islamist group has been influential and prominent within the Syrian uprising. Sheikh was one of the founding members of Ahrar al-Sham and, until his defection last month, one of its leaders.

Ahrar al-Sham is now split into two factions – those who favour greater pragmatism (and, along with this, compromise and moderation) and those who are doggedly doctrinaire. It faces other challenges, too, because HTS has adopted an aggressive posture towards rival anti-Assad forces. In recent weeks its fighters, targeting the Free Syrian Army, Ahrar al-Sham and other units, have sought to consolidate control over the entire province of Idlib in north-western Syria, near the border with Turkey. This is the most significant rebel redoubt in the country after the fall of Aleppo.

“Al-Qaeda is eating us,” an official with the US-backed moderate rebel group Fastaqim told the Washington Post last month, explaining why his fighters had joined an alliance with Ahrar al-Sham despite its more hardline views.

The consolidation among the rebel groups, and the drift towards greater extremism, stem directly from what happened in Aleppo late last year before it was finally reclaimed by Assad’s army. When regime fighters, aided by Iranian-backed militias and Russian troops, managed to encircle and besiege eastern Aleppo, Assad enacted an already tried and tested policy: submit or starve. For months, hundreds of thousands of civilians trapped inside the city survived on dwindling supplies while Syrian and Russian warplanes dropped barrel bombs and bunker busters capable of ­destroying underground medical facilities.

So great was the suffering that, when the regime made its final push on Aleppo just before Christmas, rebel pockets crumbled much faster than anyone had predicted. After an evacuation deal was agreed, tens of thousands of civilians moved into the rebel-held Idlib, to the west. A minority went to regime-controlled parts of Aleppo.

The shifting dynamics of the war present a significant challenge for Syria’s beleaguered and dwindling revolutionaries, who find themselves caught between the twin barbarisms of Assad and the jihadist groups. Although there remains an alphabet soup of groups operating in Syria, few have any significance. In Idlib, the only groups realistically capable of commanding authority or administering rebel-held territory were JFS and Ahrar al-Sham. With the latter in free fall, it seems that the spoils will go exclusively to Hayat Tahrir al-Sham.

This marks a dangerous pivot in the Syrian Revolution. The pragmatic aspects of the opposition are being overtaken by a bullish and avowedly jihadist movement that is not only dogmatic in its approach to scripture, but also not prepared to abide minorities. The ascendency of HTS heralds an end for the opposition’s backers in both the West and the Gulf, who will shy away from supporting an alliance that so brazenly incorporates a former al-Qaeda affiliate. Already, the US, Saudi Arabia and Turkey have suspended support to moderate rebel groups, fearing that supplies will fall into the hands of extremists.

“There is now a strong likelihood that [this] will be remembered as the moment when Western and Arab states turned away from the Syrian opposition, sealing its fate,” Aron Lund, a fellow at the Centre for Syrian Studies at St Andrews University, noted recently.

***

The extremist hijacking of the rebellion is precisely what Assad wanted. For years he tried to portray everyone opposed to his regime as a terrorist, arguing that they were inspired first by the Muslim Brotherhood and then by al-Qaeda and IS.

It was a deft move. When the protests began in 2011 as a principally secular and student-led movement, Syria’s Ba’athists faced an existential threat. As had occurred elsewhere in the Arab world, the international community was on the side of the revolutionaries. The Assad regime had to find a way to make the opposition unacceptable to the West. Over a long period and after much suffering, it has succeeded in achieving precisely that, by peeling progressives away from the opposition and fomenting the jihadist threat within.

Radical groups are now consuming those that have otherwise evaded the regime, a number that grows smaller by the day.

A report published last month by Amnesty International describes the methodical extermination campaign waged by Assad against peaceful activists detained in his most disreputable prison – Sednaya, where Sheikh was once held. The report documents how up to 13,000 people were hanged in the prison between 2011 and 2015, usually after severe beatings and torture.

“The victims are overwhelmingly civilians who are thought to oppose the government,” the Amnesty report states. “Since 2011, thousands of people have been executed in mass hangings, carried out at night and in the utmost secrecy.”

The executions are believed to happen in groups of 50 at a time. It is thought that a further ten prisoners die every day under torture, or from the squalid conditions ­inside Sednaya, including malnutrition, overcrowding, poor sanitation and lack of medical care.

Assad’s destruction of the civilian component from the opposition has, perversely, helped his standing in the international community. He is now able to cast himself as the last guarantor of Syria’s delicate and secular social palimpsest, a particular contrast to the millenarian mania of Islamic State and al-Qaeda.

The full extent of his rehabilitation became apparent last month when the Foreign Secretary, Boris Johnson, signalled a potential change in UK government policy while giving evidence to the House of Lords select committee on international relations.

“It is our view that Bashar al-Assad should go. It’s been our long-standing position. But we are open-minded about how that happens and the timescale on which that happens,” Johnson said. This included an acceptance that Assad should be allowed to run for the presidency again. The statement marked a dramatic shift in British policy towards the conflict since it first began. “I have to be realistic about how the landscape has changed,” Johnson said.

Donald Trump has spoken repeatedly of his fears about the terrorist threat emanating from Syria: he wants to confront extremists operating in the ravaged country. Against this backdrop, it is easy for Assad to present himself as a beleaguered, secular president fighting a jihadist insurgency.

Since winning back control of Aleppo in December, Assad has seemed more emboldened than at any other point in this long conflict. The regime is concentrating its efforts nearer to Damascus. A five-week bombardment allowed the regime to retake Wadi Barada, a highly strategic area about ten miles north-east of Damascus that is one of the capital’s sources of water, in late January. Assad is now focusing on Ghouta, another district near the capital, where the regime’s forces are alleged to be using chlorine bombs as chemical weapons against the besieged population.

Given the recent military gains, can ­Assad achieve his stated aim of restoring government control over the whole of Syria? That remains an altogether more challenging and ambitious task, not least in the east, where IS remains strong.

Though it is tempting to believe reports that IS is in terminal decline, this belies the facts. The group is under pressure in Iraq and is losing territory in Mosul, its main stronghold in the neighbouring country. It is likely that Iraqi forces will eventually recover all their territory, driving IS back into its Syrian redoubts.

But the social and political dynamics in Iraq are different from those in Syria, where IS is not only more entrenched but is facing a weaker, less cohesive adversary. Assad is already stretched and fighting on multiple fronts. He cannot afford to divert significant forces to fighting Islamic State, nor is he inclined to do so. Indeed, he is now almost entirely dependent on external support. Not only did he require Russian assistance in Aleppo, but there was much broader support from Shia militias such as Hezbollah, as well as elite Iranian forces. Whereas Russia’s involvement has diminished since Aleppo was recaptured, the Iranians are now far more heavily invested – emotionally and religiously – in the conflict. Within days of Aleppo falling, one of Iran’s most senior army commanders, General Qasem Soleimani, was pictured in the city.

By contrast, Assad is yet to visit. His chief priority remains the capture and control of what has been termed “useful Syria”, the spine of economically important cities and towns running along the western frontier from Deraa, near the border with Jordan, all the way up to Aleppo.

While Kurdish troops have made gains against Islamic State in Syria, they lack the firepower and resources needed to overcome the group decisively. Given the Turkish government’s immutable opposition to empowering Kurdish forces, this is unlikely to change. And IS has demonstrated its resilience and capacity to adapt.

It is sometimes easiest to think of the various moving parts of the Syrian conflict as the air inside a balloon: squeeze one part, and you merely move the air elsewhere. Although Russian and Syrian forces were successful in retaking the historic city of Palmyra last year, once they turned their attention towards Aleppo IS returned. Its destruction of Palmyra’s cultural heritage was more intense during the second occupation than when it previously controlled the city. (Syrian soldiers and their allies recaptured Palmyra a second time early this month.) Yet IS has also made smaller gains in other areas, such as the eastern province of Deir az-Zour, where its fighters pushed through regime lines and encircled a military airbase.

These are ominous lessons for military planners in Damascus, suggesting that the residual influence of groups such as Islamic State and Hayat Tahrir al-Sham will continue to resonate for years to come.

The fall of Aleppo may well have marked a turning point in the Syrian conflict – but only towards a more draconian and jihadi-led armed opposition.

Shiraz Maher is an NS contributing writer, a member of the department of war studies at King’s College London and the author of “Salafi-Jihadism: the History of an Idea” (C Hurst & Co)