Our intelligence community does assess with varying degrees of confidence that the Syrian regime has used chemical weapons on a small scale in Syria, specifically the chemical agent sarin. This assessment is based in part on physiological samples. Our standard of evidence must build on these intelligence assessments as we seek to establish credible and corroborated facts. For example, the chain of custody is not clear, so we cannot confirm how the exposure occurred and under what conditions. We do believe that any use of chemical weapons in Syria would very likely have originated with the Assad regime.From the letter sent by Miguel E. Rodriguez, Assistant to the President and Director of the Office of Legislative Affairs to Senator John McCain and Senator Carl Levin on April 25, 2013.
And what we now have is evidence that chemical weapons have been used inside of Syria, but we don't know how they were used, when they were used, who used them. We don't have a chain of custody that establishes what exactly happened.From President Obama's April 30, 2013 press conference.
"Our investigators have been in neighboring countries interviewing victims, doctors and field hospitals and, according to their report of last week which I have seen, there are strong, concrete suspicions but not yet incontrovertible proof of the use of sarin gas, from the way the victims were treated," Del Ponte said in an interview with Swiss-Italian television.From a Reuters article about statements made this weekend by Carla del Ponte who is a member of the Independent International Commission of Inquiry on the Syrian Arab Republic.
"This was use on the part of the opposition, the rebels, not by the government authorities," she added, speaking in Italian.