commander actually instructed one of the men in australia to dis% this gas in a confined space, potentially public transportation. the men had not successfully built this device because it's just a very difficult thing to achieve. even if you're in a lab setting. but chilling to hear the details. they wanted it in that confined space to kill the maximum amount of money. >> have there been other examples of isis trying to use this chemical? >> no. i mean, there have not been any kind of plots from isis. there was an al qaeda poison gas plot against the new york subway in 2003, but that, again, was an aborted plot. the high command of al qaeda decided they weren't going to go through that. but with al qaeda developing these poison gas techniques before 9/11, the concern has been that ooisds with all their