We're moderate, see? Syrian 'rebels' parade the severed heads of ISIS members

Rebel groups battling the Islamic State in Syria have proudly paraded the severed heads of their defeated enemies, in the latest sign that all sides in the conflict are resorting to shocking barbarism.

A coalition of anti-Assad forces were stationed in the town of Azaz, close to the Turkish border, when ISIS militants prepared to carry out a suicide bomb attack followed by a massive assault.

But the rebels were tipped off about the attack in advance and were prepared for the jihadis when they arrived - slaughtering them in the streets of the Azaz before posing with the extremists' severed heads and displaying their mutilated corpses in the centre of the city.

Large crowds of cheering locals took to the streets of Azaz in the aftermath of the failed attack, which was actually under the control of ISIS for several months in 2013.

The ritual humiliation and public exhibition of the butchered corpses was in fact highly symbolic - with the jihadis' severed heads displayed in exactly the same location that ISIS themselves would show off the bodies of those they had brutally executed after Friday prayers.

Describing the attack, one anonymous rebel fighter told VICE News: 'Last night, [ISIS] sent a suicide truck to Sawran, which is the frontline now next to Azaz, but we had info of the operation,'

'So they targeted the truck with a missile... Then the fighters following the truck were caught,' he added.

On the subject of the subsequent beheadings of ISIS fighters, the rebel soldier said: 'It is not the way we act... but it's sort of revenge for all the civilians and leaders they killed.'

The news comes as US-led aircraft bombed ISIS fighters while the jihadis were battling rival Syrian rebels, including Al-Qaeda loyalists, in a first such intervention, a monitoring group said.

The Syrian Observatory for Human Rights described the overnight raids in northern Aleppo as an intervention on the side of the rival rebels, which include forces who have been targeted previously by US-led strikes.

'The coalition carried out at least four strikes overnight targeting IS positions in the town of Suran,' the UK-based Observatory said.

The US military, in a statement, said an air raid near Aleppo destroyed an ISIS ant-aircraft artillery piece and a jihadist fighting position.

'It's the first time that the international coalition has supported non-Kurdish opposition forces fighting the Islamic State,' Observatory director Rami Abdel Rahman told AFP.

He said at least eight IS fighters were killed in the strikes and another 20 were injured.

Syria expert Thomas Pierret said the raids showed Washington was intent on preventing IS from expanding in Aleppo province, which is currently largely divided between regime and rebel control.

'Washington seems really determined to stop IS from advancing against the rebels in Aleppo,' said Pierret, a professor at the University of Edinburgh.

The strikes showed Washington's 'pragmatism', he said, noting that Al Qaeda affiliate 'Al-Nusra only constitutes a small part of the rebel forces that are fighting IS,' in Aleppo, with moderate forces holding more territory.

Syrian state TV said government forces launched air strikes near Suran on 'terrorists', the term used by Damascus for all those fighting President Bashar al-Assad. It gave no further details.

ISIS captured Suran a week ago and has been fighting an alliance of rebels including Al-Nusra and Islamist Ahrar al-Sham in the surrounding area.

Both Al Nusra and Ahrar al-Sham have been targeted in US-led raids and like ISIS, Al-Nusra is blacklisted as a 'terrorist organisation' by Washington.