That message looks like PysOps to me. The claim that "one third of your country will be irradiated" indicates the writer knows little or nothing about nukes. Hiroshima-type fission nukes produce very little radioactive fallout. The only time significant fallout has actually been produced by nukes is when some huge hydrogen bombs were tested out on islands in the Pacific. So there is no way that a few small nukes could irradiate a large area of the US. Indications are that the current serious threat is from conventional explosives and chemical weapons, possibly combined into a chemical weapons bomb.