This is not the attack of August 21 which is the given causus belli for Syria. This is an earlier attack.
Unfortunately, this report has not been released to the public, so all we have to go by is a released summary.
Two things raised: the released summary of the report says the sarin formula appears to be old - WWII vintage. The Russians say it is similar to what the Western powers used during WWII.
Except: the western powers didn't discover nerve agents until AFTER WWII. Unless by Western Powers the Russians mean Nazi Germany, which was ahead of the Allies in the development of CW. Experts contacted by McLatchy suggest that perhaps this means the sarin was manufactured in a way with which the Russians were not familiar.
The other issue raised is that the Russians say the explosive used in March appears to be RDX, which is expensive stuff. It's not normally used by military chemical weapons for that reason.
The Russians say they followed agreed-upon UN protocols in performing this analysis. The UN inspectors who have been studying the Damascus attacks of August 21st were in Syria to collect data for this earlier event near Aleppo. Those inspectors have not released their results for either attack as of yet.
Caveat: if you asked me who I trusted in a 3 way contest between Vladmir Putin, Dick Cheney, and Lucifer, Prince of Darkness, Putin might lose.
No - cancel that. Cheney loses. But Putin might finish behind LPoD.
Having said that, this is supposed to be a technical document with full support for the scientific conclusions. We'll have to wait until it's released to understand that better.
My conclusion: this is another reason to, at a minimum, delay action in Syria. If the Russians do have credible evidence of rebel use of sarin, and delivery via rockets, that certainly muddies the waters. The UN inspectors, as noted, have been to both sites and should be able to tell us if the sarin used in the two attacks seems to be chemically similar.