Good that the US is taking proper defense measures, but come on, North Korea also seems to be threatening every other country it can. They seem like a little kid looking for attention.
Toxicity is the degree to which a substance can damage an organism. Almost anything can be considered "toxic." What is important, is how it is used/consumed. For example, water is a necessary key to sustaining life. However when consumed in very large quantities, toxic effects can occur leading to death.. The chances of this happening are very unlikely, however death from merely drinking water has occurred. Hope this puts things into more of a perspective.