The Obama administration, searching for support from a divided Congress and skeptical world leaders, says its own assessment is based mainly on satellite and signal intelligence, including indications in the three days prior to the attack that the regime was preparing to use poisonous gas.
But multiple requests to view that satellite imagery have been denied, though the administration produced copious amounts of satellite imagery earlier in the war to show the results of the Syrian regime's military onslaught.
The Obama administration maintains it intercepted communications from a senior Syrian official on the use of chemical weapons, but requests to see that transcript have been denied. So has a request by the AP to see a transcript of communications allegedly ordering Syrian military personnel to prepare for a chemical weapons attack by readying gas masks.
The assessment, also based on accounts by Syrian activists and hundreds of YouTube videos of the attack's aftermath, has confounded many experts who cannot fathom what might have motivated Assad to unleash weapons of mass destruction on his own people — especially while U.N. experts were nearby and at a time when his troops had the upper hand on the ground.
Hisham Jaber, a retired Lebanese army general who closely follows Syria's war, said it would be "political suicide" for the regime to commit such an act given Obama's warning. He also questioned U.S. assertions that the Syrian rebel fighters could not have launched sophisticated chemical weapons.
Some among the estimated 70,000 defectors from the Syrian military, many of them now fighting for the opposition, could have been trained to use them.
http://news.yahoo.com/lingering-doubts-over-syria-gas-attack-evidence-072755287.html