It does not appear to be a chemical weapons attack , expert said . Professor says he 's confident chemical weapons have been used , but no more . If the OPCW were to conclude that chemical weapons had been used , the debate would then turn to who used them . Russia , China have signed the Chemical Weapons Convention .
It does not appear to be a chemical weapons attack , expert said . Professor says he 's confident chemical weapons have been used , but no more . Russia , China have signed the Chemical Weapons Convention .