Six weeks have passed since the US-led coalition began its strikes against Islamic State (IS) militants and other jihadist groups in Syria, but recent developments in the stricken country confirm that the mission is facing huge challenges, as BBC Arabic's Feras Kilani reports
"We are vanishing before the eyes of the whole world, including our friends in the US," a disappointed moderate commander told the BBC over the phone, after his group's defeat by the Nusra Front, al-Qaeda's affiliate in Syria.
Al-Nusra has achieved a massive victory over the past week in Idlib province by defeating the Syrian Revolutionary Front (SRF) and the Hazm movement, two of the strongest moderate armed groups backed by US.
A video uploaded on YouTube shows Jamal Maarouf, leader of the SRF, explaining that he ordered the retreat of his fighters from their bases in the town of Deir Sonbol in order to "prevent the shedding of more bloodshed".
But al-Nusra-related accounts on social media talk of the arrest of dozens of Mr Maarouf's fighters, and the defection of others to join the group that took control of all the towns of Jabal al-Zawiya region in Idlib.
Two sources in Syria denied to BBC reports on social media that Mr Maarouf himself has been arrested by al-Nusra. They said Mr Maarouf was still trying to mobilise his fighters on the borders between Hama and Idlib provinces, assisted by Commander Methqal al-Abdallah.
Jamal Maarouf accuses Abu Mohammed al-Julani, the leader of al-Nusra, of "occupying" the area retaken from the regime's forces by the SRF three years ago.
The Nusra Front bases in this area were targeted by US-led air strikes on 23 September, the first operational day for the coalition against the extremists in Syria, but there are no reports of any more strikes after that.
It is notable that the US has not tried to save the SRF despite the fact that its warplanes have not left the Syrian skies, helping the Kurds in their fight against IS in Kobane.
The Nusra Front, with help from smaller jihadist groups, has managed to seize the majority of the towns and villages south, west and east of the city of Idlib, while the city itself is still under the control of the regime.
'A tragic end'
Sources inside Syria confirmed to the BBC that al-Nusra defeated the Hazm movement earlier this week, adding that al-Nusra seized a large cache of lethal weapons supplied to Hazm by the Americans, including advanced anti-armour missile systems.
Recently the Hazm movement tried to help Jamal Maarouf to counter al-Nusra's attack, but stopped after mediation by some other armed groups' leaders. Al-Nusra showed them no mercy.
"It was a tragic end", as one of the defectors described it to the BBC.
Hazm's leader Abdullah Ouda, along with hundreds of his fighters, were holed up in their stronghold in a forest near the village of Khan al-Sobol on Saturday afternoon.
They were expecting everything - apart from what happened in the later hours, the defector added.
"It was chaos when they realised that al-Nusra militants were surrounding them from all directions", he said.
"Ouda tried his best to convince the rebels to defend their base, but hundreds of them defected, others escaped. By the evening he had to leave the base in a convoy with only fifty fighters and head to Aleppo."
A few hours later he sent his assistant Abu Abdullah al-Homsy to negotiate with al-Nusra to leave the base, but they arrested him. He was transferred the following day to a Sharia court.
As in Deir Sonbol, al-Nusra seized dozens of tanks and armoured vehicles, as well as a huge amount of ammunition from the Hazm base in Khan al-Sobol, a large part of it supplied by the US.
"Now Hazm's leader has threatened all the armed groups in the area that he will withdraw his forces from Aleppo to counter the Nusra attack," the defector said, before adding that it would be an opportunity for the Syrian government to complete its seizure of the city.
The situation in the area had been boiling slowly for months between al-Nusra and other jihadist groups on one hand, and so called "moderate armed groups" on the other.
"Al-Nusra's decision to attack us came on 23 September, immediately after the first strike by the West against their bases in Idlib," one of Hazm's leaders, who refused to be identified, told the BBC.
"Al-Nusra accused us of leaking security information about their bases and movements to the West," he said.
Despite the movement's close relationship with the US, Hazm condemned the strike against al-Nusra in a statement issued the same day.
"The only effect the statement had was to ruin our contact with the US mediator who refused to answer all our calls," the senior Hazm source said. "We failed to convince al-Nusra that we were not spies for the US, and the US refused to help us any more."
He still cannot understand or justify the US decision to start the strikes without co-ordination with their allies on the ground.
But on the other hand, the opposite attitude from other armed groups did not make any difference.
Jamal Maarouf, who announced the war against IS even before the coalition started targeting them in Syria, stayed silent after the strikes against al-Nusra bases, and was presumed to have accepted the moves.
He was one of the most strategic allies the US had, but this did not help him and the SRF to survive, as the recent developments showed.
Mr Maarouf accused al-Nusra of co-ordinating with IS in its attack, despite the conflict between the two militant groups.
The UK-based Syrian Observatory for Human Rights (SOHR), which monitors casualties in the Syrian war, said that fighters from IS helped al-Nusra in the attack against SRF and the Hazm movement as well.
Whether they are co-ordinating or not, the map of Syria shows that with the exception of the territories still under President Assad's control, most of the country is now dominated by the jihadists.
Now, it looks as though the defeat of the SRF and the Hazm movement will make it very difficult for the coalition to find any moderate armed groups to train for the next stage in its war against IS and al-Nusra.