A gruesome video (warning: graphic content) posted Wednesday shows Syrian rebels in the eastern province of Deir al-Zor invoking sharia law as they sentence soldiers loyal to President Bashar Assad to death. The soldiers, kneeling and blindfolded, are then shot in the back of the head by a rebel whose face is hidden by a black balaclava.

The executioners claim to belong to the al-Nusra Front (Jabhat al-Nusra), a Syrian rebel cell associated with al-Qaeda, Reuters reported Thursday.

With the civil war in Syria between Assad’s forces and myriad insurgent groups entering its third year, and as both sides struggle for the upper hand in media coverage, increasingly unpalatable videos have been surfacing that expose the war at its most brutal.

A similar video circled the web on Tuesday, showing rebels from the Raqqa province publicly executing three men purported to be military officers.

The insurgents, who in both cases reportedly belonged to al-Qaeda-sponsored factions, are seen proclaiming that the executions are in retaliation for massacres perpetrated by the Assad regime, in particular the killing of Sunni civilians in the coastal city Bannias earlier in May. The number of dead in the Bannias massacre is approximated at totaling least 145, according to the Syrian Observatory for Human Rights, a pro-opposition monitoring group.

The stark horror of the struggle was also underlined early this week with the widespread circulation of a graphic video apparently documenting a Syrian rebel cutting an organ out of the corpse of a slain regime soldier and taking a bite out of it. The rebel fighter himself later confirmed that this was the case.

According to the Syrian Observatory for Human Rights, some 80,000 people have been killed so far in the conflict.