The UN claim
s that some aspects of the UN report are indisputable, according to UN spokesperson Martin Nesirky, namely that rockets loaded with sarin gas were used in the attack:
"The findings in that report are indisputable. They speak for themselves and this was a thoroughly objective report on that specific incident."
Of course even if this fact is indisputable, it does not in itself settle who launched the rockets or even if all the sarin gas was delivered in that manner. But it is not really indisputable I should think in the first place. According to this article
the report notes:
“The time necessary to conduct a detailed survey of both locations as well as take samples was very limited. The sites have been well travelled by other individuals both before and during the investigation. Fragments and other possible evidence have clearly been handled/moved prior to the arrival of the investigation team”.
on page 22 of the report also makes similar comments and goes even further:
As with other sites, the locations [had] been well travelled by other individuals prior to the arrival of the Mission. Time spent on the site was … limited. During the time spent at these locations, individuals arrived carrying other suspected munitions indicating that such potential evidence [was] moved and possibly manipulated. 
The full UN report can be found in a very readable form here.
Note that this caveat appears in a detailed discussion of the munitions used. How many main stream reports will even mention these caveats?
The US repeatedly insisted that the investigation was too late and that the Assad regime would have destroyed the evidence and specifically by artillery bombardment. And yet rockets were found in craters in such form that the angle of entry was able to be measured to determine where approximately they came from which turned out to be two government held areas. Evidence that might implicate the Assad regime was well preserved it would seem. Yet no one in the main stream press would dare suggest that some of the evidence may have been deliberately planted by the rebels even though the report itself suggests this possibility.
The rockets used, at least in some cases, seem to have been made in Russia. However, there is at the least the possibility that the rebels were able to capture some rockets of this sort. Just dealing with this one issue has already made this article long so I will briefly consider another issue. When the first videos of the gas attack surfaced many chemical experts noted that if sarin were used it was not military grade sarin. There are many references but here
is a recent comment:
A footage showing how people with no protective clothing or respirators inspect bodies makes Western specialists certain that in the case of military sarin gas these people would die as well. This means that the opposition could easily obtain non-military sarin gas to perpetrate this attack. Both Agénce France Press and Israeli Haaretz reported this, but again, it diverts too much from the mainstream point of view in the media, which is why it was totally ignored.
Barack Obama's national security adviser, Susan Rice, said that
the technical evidence of high grade sarin that was revealed in the report "reinforces our assessment that these attacks were carried out by the Syrian regime, as only they had the capability to mount an attack in this manner." Unfortunately, there is no reference to where in the report that the sarin was said to have been high grade. Assuming she is correct, the question number 16
asked about the report by Global Research seems relevant:
If the sarin had been military grade, then why did the people moving the victims, without any protective clothing or masks, not die instantly?
They hardly need to die instantly but the point seems correct that the people attending to the victims should have been badly effected by the gas. This surely indicates that the gas was not of military quality. Others have pointed out that if it had been then there would have been many more casualties.
Russia rejected the report and insisted
that it has evidence that the rebels have carried out the attacks. The Russians had given a large dossier to the UN on an earlier alleged attack near Aleppo which it insists was carried out by rebels using sarin. Some evidence from a UN investigation pointed in the same direction. However, so far the Russians, unlike the US and France, have not made their evidence publicly available even in summary form. The UN inspectors will be returning to Syria to investigate the incidents that they were originally scheduled to look at plus new cases. Reports on these may shed more light on what happened in these other attacks.