Under what’s described as a meticulously guarded process to protect the chain of custody, the samples were sent to four laboratories for testing. Eighty-five percent of the blood samples tested positive for sarin, according to the findings. Put another way, of 34 patients who had signs of poisoning, “almost all tested positive for exposure to sarin.”
The British ambassador to the United Nations said after he was briefed on the report that the head of the investigation, Dr. Ake Sellstrom, had described the sarin in the assault as of better quality than that used in a 1995 Tokyo terrorist attack or in an Iraqi attack on Kurdish villages in 1988.
“This was no cottage industry use of chemical weapons,” he said, adding that it confirmed the British government’s belief that only Assad’s military could have launched the attack.
The U.N. team also examined impact sites and munitions, and collected 30 soil and environmental samples, “far more than any previous such United Nations investigation.” A majority of the rockets or rocket fragments the team examined were confirmed to contain sarin.
The U.N., Human Rights Watch and a number of independent arms-control monitors have determined that the chemical weapons attack in question was delivered by a combination of two unguided surface-to-surface rocket systems – 140 mm and 330 mm – both of which are known to be in the arsenals of Iran, Syria and the militant group Hezbollah but which haven’t been claimed or alleged to be in the hands of the rebels, who would find such weapons useful in the siege-style battles common to the civil war.
Without directly pointing the finger, the report left little doubt that the rockets carrying the sarin payload were fired from Syrian government territory and that at least some of them were of Russian manufacture. A photograph in the report showed Cyrillic lettering on the engine of a 140 mm rocket that the inspectors had examined.
Eliot Higgins, a British blogger who writes on the weapons used in the Syrian civil war, wrote on his Brown Moses blog that the evidence for the Syrian government’s responsibility far outweighed suggestions of rebel culpability. Recounting the details of the two types of rockets found – one of likely Russian manufacture, the other possibly of Iranian origin – Higgins noted that the rebels have never been known to use either. He also pointed out that rockets similar to the possible Iranian rocket were found at the site of an Aug. 5 alleged chemical attack.
He said the warheads of similar rockets photographed at the scenes of other attacks all had split open the same way, an intentional design feature that was "beyond anything the opposition has manufactured themselves."
The settings on the guidance systems as reported by the inspectors made clear that the rockets were fired from the northeast of Damascus – where the government is in control – to the eastern suburbs, which are under control of rebel forces, said Greg Thielmann, a senior fellow at the Arms Control Association, a nonpartisan research center in Washington.
The advocacy group Human Rights Watch said in a report last week that the Soviet Union had shipped numerous 140 mm rockets and hundreds of rocket launchers to Syria. But Thielmann noted that it wasn’t clear whether Syrian engineers had modified the original Soviet design.