Is the Lt Col a reliable source according to the wiki guidelines Anyway i m no legal expert so I m not going to try to build a case why phosphorus bombs are chemical weapons The fact that the OPCW thinks that pb used against people makes them chemical weapons should be enough It s unlikely that the organisation charged with the implimentation of the CWC would say something that would contradict the treaty I can give you a quote from wthe wikipedia article Under this Convention any toxic chemical regardless of its origin is considered as a chemical weapon unless it is used for purposes that are not prohibited an important legal definition known as the General Purpose Criterion With my imperfect legal knowledge I think this the reason why the OPCW thinks that the use of pb against people makes it a chemical weapon pb short for phosphorus bomb