weapons experts, who thought they were consistent with a nonconventional weapons attack. >> so what does this mean? the president has talked about a red line and has been careful in discussing a red line to talk about mass casualty events, to talk about systemic deployment. if we are seeing something like this, if it is confirmed, it seems to me is the most systemic mass attack, deployment of chemical weapons. what does that mean for the red line the president has noted? >> reporter: this would be a totally different scale of events. in the past we've talked about chemical weapons being used to kill one, two, five people in numerous attacks. that always struck observers as a bit strange, more of a terror tactic than a tactic of war. using a limited amount of chemical weapon to scare your enemy instead of creating mass casualties. if this, in fact, is confirmed, this would be a different kind of attack.