president barack obama has been meeting his national security visor advisors to consr his options.efense minister says that they're ready to act ton barack obama's orders. >> barack obama has asked the defense department to prepare options for all contingencies. we have done that. again, we are prepared to exercise whatever option if he decides to employ one of those options. >> obama has said any use of chemical weapons in syria would constitute the crossing of a redline. but washington says it still needs proof chemical weapons were used in this recent attack. evidence is strong from pictures and testimonies from witnesses. now the organization doctors without borders say hospitals hs it supports in damascus treated many patients with neuro toxic symptoms on the night of the alleged attack. the aid group says 355 of those people died. >> pinpoint pupils, access saliva, respiratory distress, convulsions, all that point towards the use of a neuro toxic agent. >> during a phone call on saturday, british prime minister david cameron and u.s. president agreed that the suspected attack