"... i don't get why this is on hn. ..." Situation awareness. Vigilance is required in an era of http://en.wikipedia.org/wiki/Asymmetric_warfare http://en.wik

"... i don't get why this is on hn. ..." Situation awareness. Vigilance is required in an era of http://en.wikipedia.org/wiki/Asymmetric_warfare http://en.wikipedia.org/wiki/Asymmetric_warfare Schneier is simply highlighting that what appear to be safe, reliable everyday industrial chemicals can in fact be used against civilians. For example check the disruptions of unintentional chemical spills in my own home town, Melbourne ~ http://www.google.com.au/search?q=melbourne+toxic+chemicals http://www.google.com.au/search?q=melbourne+toxic+chemicals then consider the effects of intentional use in a large city. With a bit of forethought this can be minimised. While the obvious chemicals like fertilisers (Ammonium Nitrate) are now controlled (you need to apply to purchase large quantities) chemicals manufactured or stored in large concentration are a potential weak spot and should be systematically plugged with minimum security guidelines.