This is more than what Obama has produced as evidence for his claims. "Russia says it's compiled 100-page report blaming Syrian rebels for a chemical weapons attack," by Matthew Schofield for McClatchy, September 5:
BERLIN — Russia says it has compiled a 100-page report detailing what it says is evidence that Syrian rebels, not forces loyal to President Bashar Assad, were behind a deadly sarin gas attack in an Aleppo suburb earlier this year.
In a statement posted on the Russian Foreign Ministry’s website late Wednesday. Russia said the report had been delivered to the United Nations in July and includes detailed scientific analysis of samples that Russian technicians collected at the site of the alleged attack, Khan al Asal.
Russia said its investigation of the March 19 incident was conducted under strict protocols established by the Organization for the Prohibition of Chemical Weapons, the international agency that governs adherence to treaties prohibiting the use of chemical weapons. It said samples that Russian technicians had collected had been sent to OPCW-certified laboratories in Russia.
The report itself was not released. But the statement drew a pointed comparison between what it said was the scientific detail of the report and the far shorter intelligence summaries that the United States, Britain and France have released to justify their assertion that the Syrian government launched chemical weapons against Damascus suburbs on Aug. 21. The longest of those summaries, by the French, ran nine pages. Each relies primarily on circumstantial evidence to make its case, and they disagree with one another on some details, including the number of people who died in the attack.
The Russian statement warned the United States and its allies not to conduct a military strike against Syria until the United Nations had completed a similarly detailed scientific study into the Aug. 21 attack. It warned that what it called the current “hysteria” about a possible military strike in the West was similar to the false claims and poor intelligence that preceded the United States invasion of Iraq.
“The Russian report is specific,” the ministry statement said. “It is a scientific and technical document.”
The statement also noted that the attention paid to the Aug. 21 attack had diverted attention from the investigation into the March 19 incident, which was the reason U.N. investigators were in Syria when the more recent attack took place.
“Unfortunately, that investigation still essentially has not begun,” the statement said....