"Cyber attack and warfare rules of engagement will undoubtedly require hundreds of pages to establish a decision framework. That being said, there are a few critical areas that will pose the most significant challenge to policy makers. One of these areas will be the level of confidence in the identification of the entity behind an attack on a nation. Tracing and tracking cyber attacks back to those responsible is not an easy task. Usually this takes months or years not minutes and hours. Current intelligence and surveillance capabilities will provide only minimal assistance in this effort."
Cyber Attacks & Warfare - Rules of Engagement