Often described as the “most senior Australian in al-Qaeda”, 33-year-old Sheikh Abu Sulayman al-Muhajir – aka Mostafa Mahamed Farag – says he is no longer affiliated with any designated terrorist group or rebel faction in Syria, but nevertheless remains on Australia’s counterterrorism sanctions list and the United States’ “specially designated global terrorist” watchlist.

Earlier this year, Abu Sulayman contacted me to thank me for what he described as my “impartial” reporting of the Syrian civil war. Although he has acted as media spokesman for the former al-Qaeda affiliate in Syria al-Nusra Front – now known as Jabhat Fateh al-Sham – I was still surprised to hear from a figure of such infamy. Colleagues from CNN and On The Ground News who have either interviewed Abu Sulayman face to face or by phone verifed he was who he claimed to be. Understanding the importance of confirming his identity ahead of my reporting our correspondence, this week he sent a video of himself naming his various aliases and stating: “I’ve been in communication with C. J. for a few months now, via my Twitter account and via Telegram.”

As he describes, we have held ongoing discussions in correspondence regarding his views of the Syrian conflict, and his experiences after leaving Australia for Syria in late 2012.

“I’m not really a company man,” Abu Sulayman wrote, explaining that since last year he had ceased working for Jabhat Fateh al-Sham, or JFS. He added that he sees his role in the five-year Syrian civil war as one of mediating and “building bridges” between disparate rebel groups, and between rebel groups and the “outside” world.

“Baghdadi has the brain the size of a peanut. He is not a sophisticated thinker. I’d describe him as having [US president] Bush’s intellect and Trump’s temperament.”

While much has been written about the Egyptian-born, Australian-raised jihadist, much of it has been based on “speculation and guessing”, according to Abu Sulayman, who expressed a desire to set the record straight.

For instance, in 2016 ABC News speculated Abu Sulayman “had to have been well known to al-Qaeda before he relocated to Syria” given he was handed a very senior leadership position within the group’s Syrian affiliate so soon after arriving in the conflict-torn country. The article also quoted Thomas Joscelyn, a terrorism analyst in the United States, who said: “The US officials that I’ve been speaking with universally think that Abu Sulayman was in fact an al-Qaeda member before going to Syria.”

When I asked Abu Sulayman what explains his meteoric rise within al-Nusra, from fresh foreign recruit to director of media relations and membership of the group’s General Islamic Council, he told me:

“There was a void; I had initiative and [al-Nusra] recognised their need for someone like me. That is about it. There are no secrets like some analysts try to make it seem. When I arrived [in Syria], there were people that held important posts but were underqualified or lacked sufficient experience, but the situation was far from perfect, and they worked with what was available. When I came, they sought to benefit from me as much as possible. We were in need of all hands on deck, so anyone who came forward would be put to work in the best place they fit.”

Abu Sulayman added that given he was older than most mujahideen who travel to Syria, and the fact he was university educated and “from the West”, made him a rare commodity in Syria at that time. “So I was given a lot of respect from day one, and being considered a Shari’ee [Islamic expert] certainly helped, too,” he said.

It was this skill set and background that gave Abu Sulayman a front-row seat to the then diplomatic quarrel between Daesh and al-Nusra’s command, a dispute that would result in the ultimate break-up between the two groups.

In late 2013, when negotiations were very much still in the balance, Daesh leader Abu Bakr al-Baghdadi summoned the Australian to a meeting in Aleppo, Syria, to help mediate the dispute between him and the leader of the then al-Nusra Front, Abu Mohammad al-Julani, for whom the US State Department recently posted a $US10 million reward for information that leads to his capture.

While much has been written about Baghdadi, a figure who is quasi-deity to his supporters and a psychopathic nihilist to most others, very few outside of his most trusted inner circle have met or had dealings with the reclusive Daesh caliph.

“I was the first to mediate between JN [al-Nusra Front] and ISIS [Daesh] to stop the bloodshed,” Abu Sulayman told me. “It was very intense at the time. He [Baghdadi] was organising meetings with various people of influence to win them over to his side. I was one of them.”

Abu Sulayman met with Baghdadi half-a-dozen times, spending 24 hours with him on one of those occasions. He provided the following startling assessment of the Daesh caliph:

“Baghdadi has the brain the size of a peanut. A serious airhead, an idiot. I seriously had my bubble burst when I met him for the first time. I expected someone much deeper. He is not a sophisticated thinker. He’s a blustering buffoon. I’d describe him as having [US president] Bush’s intellect and Trump’s temperament. He was always ranting about the most childish issues. ‘Bring Julani to me now,’ he’d say. ‘How dare he not come and see me face to face?’ Very childish. And a horrible liar.”

Abu Sulayman also asserted: “Baghdadi is not ISIS,” claiming his title of caliph is “just a name” and that “other people are running the show”. When I asked whether these “other people” were Saddam-era Baathists, he replied: “Not Baathists. Others in the organisation.”

Much of Baghdadi’s legitimacy and credibility is built on his attainment of a PhD in Islamic studies. When I offered this as a counter to Abu Sulayman’s unflattering assertion about the leader’s intelligence, he replied: “His PhD is from Iraq. It’s like getting a medical degree from Russia. He can recite the Koran. But that is the most basic science in Islam. You can teach that to a seven-year-old.”

Elsewhere, Baghdadi has been described as a “terrorist mastermind”. He has been compared to the Great Khan of the Mongols, Genghis Khan, who ruled over the largest contiguous empire on earth at the time of his death.

“Baghdadi has no strategic long game,” Abu Sulayman countered. “He made up the whole caliphate ‘strategy’ as a way to get back at Julani and Zawahiri [al-Qaeda’s leader Ayman al-Zawahiri]. There’s never a strategy behind a kneejerk reaction.”

Unsurprisingly, Abu Sulayman welcomes the demise of Daesh. He described the group as a “bunch of criminal thugs acting in the name of Islam”, and believes their lust for indiscriminate acts of violence fails to serve the interests of what he calls “the cause”, the goal of establishing a legitimate Islamic nation in what is still, at least for now, Syria.

“The Islamic ummah at large needs to work together to establish the foundations of what will be an extremely complex system,” Abu Sulayman said. “A caliphate is not necessarily the ultimate goal now. Sovereignty is the objective. Being able to independently rule our lands by our belief system, without serving the interests of another state. We don’t want to be a satellite state. Is that too much to ask?”

When I asked whether al-Qaeda would have any involvement in this would-be future Islamic nation, Abu Sulayman said, “I can tell you with 100 per cent certainty, al-Qaeda no longer exists in Syria. The media said [the renaming of al-Nusra to Jabhat Fateh al-Sham] was a game, a PR strategy. It’s not. But the media get things wrong too often anyway. I put all my effort into that goal. Zawahiri is not the emir of JFS. He is not a member. He has no authority. He has no influence.”

He explained that the relationship between these rebel groups in Syria and al-Qaeda was rooted only in logistical expediency, a need to attract mujahideen to the country in order to help in the fight against the Syrian dictator Bashar al-Assad. “The need for that no longer exists,” Abu Sulayman told me, a claim he also echoed in a 2016 interview with The Intercept. “The break [from al-Qaeda] was also required in order to fulfil our communal obligations to Muslims in Syria.”

While there are many Muslims who leave Australia for Iraq and Syria attracted to the violence and lawlessness Daesh promotes, Abu Sulayman claims different motives.

It is not clear he has ever taken part in what could be deemed terrorist violence – if his spokesman position can be considered separately – and based on the dozens of sermons he has presented online, he has not called for attacks against innocent civilians in Syria or elsewhere. The Australian government believes he has recruited Australians to fight for al-Nusrah and has solicited funds to finance the group’s activities, though he denies these claims.

Abu Sulayman describes a religious duty to provide whatever aid or assistance he can to those being attacked by Assad’s barrel bombs and fighter jets. At the least, he offers a unique insider’s perspective to some of the struggles for power in the region.