CNN CNN Newsroom With Fredricka Whitfield August 15, 2015 15:43:00
Chemical agent that isis has used before in battle or precursor chemicals the building blocks of mustard gas. some commanders downplay the battlefield effect, but such we weapons can spark a new level of fear for kurdish forces already locked in a stalemate with isis. >> their m.o. is basically strike fear into the hearts of everybody, no matter what the tactic or technique is. >> reporter: the u.s. has not yet determined where or how isis obtained a mustard agent. it is possible they overran stockpiles not destroyed under the 2014 agreement to rid syria of chemical weapons. it's also possible...