>If you look at the list of target nations they include non-nuclear countries (Syria, Iran, etc).
US policy is to respond to non-nuclear WMD attacks with nuclear weapons, and it's a good policy. Because otherwise we would need to develop and maintain large stocks of chemical and biological weapons if the policy was to respond to WMD with the same kind of WMD.
US policy is to respond to non-nuclear WMD attacks with nuclear weapons, and it's a good policy. Because otherwise we would need to develop and maintain large stocks of chemical and biological weapons if the policy was to respond to WMD with the same kind of WMD.