Rebel divisions in Idlib threaten to further weaken an already fragile opposition in northern Syria, analysts have said, ripping two ostensible allies apart and throwing into question the direction and shape of the remainder of the armed rebellion.

Over the past week, Jabhat Fateh al-Sham (JFS) and Ahrar al-Sham, two of the most powerful rebel outfits in Syria who have long fought side by side against government forces, have turned on each other in Idlib, the country's last rebel-held province.

The fracture comes at a time when the international community is placing increasing pressure on rebels to distance themselves from JFS and enter into political negotiations with the Syrian regime.

Trilateral talks aimed at consolidating a nationwide ceasefire - a ceasefire that excludes JFS - wrapped up in Kazakhstan's capital of Astana the day before the clashes broke out. And while the aim of the meeting was to pave the way toward UN-led negotiations on February 20, it remains unclear whether any elements within the two major rebel factions in the north will participate in the process.

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Clashes between JFS and other rebel groups, including Ahrar al-Sham, snowballed across the north after JFS fighters launched a preplanned assault on Jaish al-Mujahideen, a rebel faction based west of Aleppo.

The infighting has left the province divided between two twisted areas of control, split between a new Salafist coalition created by new JFS, a group formerly known as al-Nusra Front that changed its name after dropping its official link to al-Qaeda, on one side, and the nationalist Islamist movement Ahrar al-Sham and smaller Western-backed factions on the other.

The new Salafist alliance created by JFS, which is united under the name Hay'et Tahrir al-Sham and includes influential factions like the Nour al-Din al-Zenki group, emerged just days after six other rebel factions that were targeted by JFS joined ranks with Ahrar al-Sham.

Analysts say the JFS attacks on other elements of the opposition were "explicitly" linked to the outcome in Astana, and have left moderate factions with difficult choices.

"The attack by Fateh al-Sham was an attempt to liquidate some of the more relevant [rebel] factions that had lent their credibility to Astana and these various other rounds of international negotiations," Sam Heller, a Syria analyst and fellow with The Century Foundation, told Al Jazeera.

"It looks like they were attempting to railroad through a consolidation of the north factions on Fateh al-Sham's terms and under Fateh al-Sham's effective leadership."

Listed as a "terrorist" organisation by the United Nations and western governments, JFS was excluded from the ceasefire established late last year by Russia and Turkey, and was highlighted as a mutually agreed upon target in a final communique signed by Moscow, Ankara and Tehran at the close of the Ankara talks earlier this month.

If Ahrar al-Sham now decides to participate in the next talks in Geneva, it will enter a much larger conflict with Hay'et Tahrir al-Sham. Hamza al-Mustafa, researcher

Ahrar al-Sham, on the other hand, has long straddled the fault line between moderate rebel groups that define themselves as "revolutionaries" and more hardline Salafist groups like JFS. While it did not attend the talks in Astana, it has been deemed a "moderate" group by Russia and receives heavy backing from Turkey.

"It probably didn't help that, presumably US, drone strikes on Fateh al-Sham have stepped up recently, which I assumed ratcheted up paranoia about rival factions and various other agents on the ground providing coordinates of Fateh al-Sham commanders and bases," said Heller.

US drone strikes targeting JFS have increased in recent weeks, one of which reportedly killed at least 100 fighters, including 10 senior commanders, in Idlib.

JFS placed the blame for the fall of Aleppo on a lack of coordination and structure among the moderate factions that held most of the city's eastern neighbourhoods.

"They all bore responsibility for the loss of Aleppo, but the narrative that they have adopted is that these MOM internationally backed factions turned out to be useless," said Heller, using the Turkish acronym for a Joint Operations Center, through which the CIA and other foreign intelligence agencies arm and coordinate with rebels in Syria's north.

Hamzeh al-Moustafa, a researcher at the Arab Center for Research and Policy Studies, argued that JFS's distrust of MOM-linked rebel factions pushed the group to declare "a new Salafist emirate".

Not only were JFS commanders worried that intelligence on whereabouts of the group's commanders and bases were being used in drone strikes, but they also believed they would be able to strip some of the more hardline elements within Ahrar al-Sham away from the group and create a larger, more ideologically pure movement.

"Al-Nusra was expecting that the hardliners in Ahrar al-Sham like Abu Jaber would push the movement to join the Nusra project," said Moustafa, referring to the former leader of Ahrar al-Sham who announced his resignation from Ahrar al-Sham on Twitter shortly after news broke that he had been named "general commander" of the new Hay'et Tahrir al-Sham coalition.

Since many of the key hardliners - who have caused ideological rifts within Ahrar al-Sham in the past - have been stripped away, the group's moderate elements may have more sway over its agenda.

"The [Ahrar al-Sham] moderates are pushing for an agenda closer to that of the Syrian people, and the hardliners in Ahrar al-Sham want to join Hay'et Tahrir al-Sham," said Moustafa.

But Ahrar al-Sham has repeatedly refused to participate in negotiations, largely due to internal divisions, and analysts are unsure if the recent change within its internal make up - its absorption of moderate Western-backed groups - and increased pressure from its regional backers will make a difference.

"One thing is for sure, if Ahrar al-Sham now decides to participate in the next talks in Geneva, it will enter a much larger conflict with Hay'et Tahrir al-Sham," said Moustafa.

Turkey, a major supporter of Ahrar al-Sham, was able to convince most of the moderate rebel factions it backs to attend the talks in Astana. But without the inclusion of Ahrar al-Sham, one of the central factions across much of northern Syria, the opposition's leverage at the negotiating table will be limited.

Ankara's shift in Syria since last summer has seen it move its priorities away from an all-out regime change towards a central focus on "the Kurdish issue" along its border region. As its rapprochement with Russia holds, it has placed increasing pressure on the Syrian opposition to "follow suit and to make Turkey's pivot effect and sustainable", according to Yazid Sayigh, a senior associate at the Carnegie Middle East Center in Beirut.

"Turkey is going to have to keep pushing the Syrian opposition further along the path of doing whatever is necessary to make it possible to have a stable holding pattern in Syria, which means finding a way of dealing with Fateh al-Sham because, otherwise, this will be a constant excuse for the regime and the Russians, if not the US, to escalate, at a time when Turkey is trying to stabilize the situation."

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The moderate opposition, which now includes many elements within Ahrar al-Sham, is at a strategic juncture.

Either it rejects the diplomatic track altogether and joins ranks with JFS-led Hay'et Tahrir al-Sham coalition, or it distances itself from JFS and continues to ally with Turkey, hoping that through negotiations - and continued military support - it can maintain territory and some degree of political influence.

And while joining ranks with the JSF may help the rebels avoid all-out infighting in Idlib, it would also cost them one of their key regional backers.

"The Turks have made it clear to these factions, inclusive of Ahrar al-Sham, but not exclusively, that if they join with Fateh al-Sham and with what is approximately al-Qaeda … they're done," said Heller.

By joining ties with JFS, these groups would effectively nullify the fragile ceasefire and open themselves up to air strikes not only from the government and its Russian backer, but also from a large cross section of the international community.

Russia would then likely support a renewed and expanded military campaign in Idlib, under the premise of attacking "terrorists", which would likely generate heavy rebel losses, civilian casualties and destruction on a level similar to what was seen in Aleppo.

"Meanwhile, though, I think Russia and the regime are comfortable with the current situation," said Moustafa.

"They can sit back and watch as their ceasefire holds and the opposition fights itself."

Follow Dylan Collins on Twitter: @CollinsDyl