It is one of the most horrifying videos of the war in Syria. It shows two men being beheaded by Syrian rebels, one of them by a child.... At the end of the film, a soldier, apparently from the Free Syrian Army, holds up the severed heads by their hair in triumph.....

The video underlines a startling contradiction in the policy of the US and its allies. In the past week, 130 countries have recognised the National Coalition of Syrian Revolutionary and Opposition Forces as the legitimate representatives of the Syrian people. But, at the same time, the US has denounced the al-Nusra Front, the most effective fighting force of the rebels, as being terrorists and an al-Qa’ida affiliate. Paradoxically, the US makes almost exactly same allegations of terrorism against al-Nusra as does the Syrian government. Even more bizarrely, though so many states now recognise the National Coalition as the legitimate representative of the Syrian people, it is unclear if the rebels inside Syria do so. Angry crowds in rebel-held areas of northern Syria on Friday chanted “we are all al-Nusra” as they demonstrated against the US decision.

Videos posted on YouTube play such a central role in the propaganda war in Syria that questions always have to be asked about their authenticity and origin. In the case of the beheading video, the details look all too convincing. Nadim Houry, the deputy director for Human Rights Watch in the Middle East and North Africa, has watched the video many times to identify the circumstances, perpetrators and location where the killings took place. He has no doubts about its overall authenticity, but says that mention of one district suggests it might be in Deir el-Zhor (in eastern Syria). But people in the area immediately north of Homs are adamant the beheadings took place there. The victims have not been identified. The first time a version of the film was shown was on pro-government Sama TV on 26 November, but it has been widely viewed on YouTube in Syria only over the past week....