The evidence came from a variety of sources, and some was collected by non-Syrians, said the sources, who like others interviewed for this report spoke on the condition of anonymity, citing strict secrecy surrounding the operation. Details about how the evidence was gathered and tested could not be disclosed without compromising ongoing intelligence operations, the officials said.
Having been famously burned by the 2003 intelligence failure over Iraq’s alleged weapons of mass destruction, U.S. analysts now approach all such claims with exceptional care, said a third administration official familiar with intelligence analysis. “You have to use sophisticated analytic techniques that account for, and carefully weigh, competing evidence and subject your findings to intense self-imposed scrutiny,” the official said.
But Western officials and diplomats also acknowledged that the lack of transparency undermined the credibility of the chemical-weapons claims.
“The chain-of-custody issue is a real issue,” said a senior Western diplomat whose government has closely tracked the Syrian investigation. But the official said the totality of the evidence “from different sources, different times, different locations” should convince the U.N. investigating body that the claims were real.
Challenge for U.N.
The key fact-finder for determining whether and how chemical weapons were used is Ake Sellstrom, a Swedish scientist and the chief U.N. weapons inspector. He must try to link the physical evidence to a verifiable use of chemical weapons inside Syria, like a criminal prosecutor assembling a case that can stand up in court.
Sellstrom is scheduled to travel next week to Turkey, the first leg in a reporting trip that will include stops in Lebanon and Jordan. There, he is expected to interview Syrian witnesses and medical professionals who claim to have treated victims of chemical-
The senior Western diplomat said Sellstrom and his team should be able to put together a “pretty coherent picture of what happened,” though the diplomat voiced frustration that it has taken Sellstrom months to send a team to the region to interview refugees.
“If we have criticism with Sellstrom, it’s that he has been very passive,” the official said.
U.N. officials continue to push for an on-the-ground inspection in Syria, even as they acknowledge the diminishing chances that the Assad government will let them in.