but that's it. >> the options that we are considering are not about regime change. >> reporter: that, some say, could backfire on the white house. >> it may give bashar al assad a propaganda advantage by saying he was able to resist the united states attacks. > > . >> reporter: the heinous use of chemical weapons. >> reporter: but so far they offered no hard evidence. >> the intelligence community is working on an assessment. >> reporter: u.s. officials tell cnn that assessment includes forensic evidence that chemical weapons were used and satellite activity at chemical weapons depots and communications of syrian forces. now, sources told me they intercepted calls between syria and military commanders and the website foreign policy has additional details reporting it was a panic call from the ministry of defense. an official there calling one of