A “cyber attack” can take any number of forms, including simple probes, defacement of Web sites, denial-of-service attacks, espionage, and destruction of data. And the term “cyber war,” though best defined as any hostile action in cyberspace that amplifies or is equivalent to major physical violence, remains equally protean, reflecting definitions of “war” that range from armed conflict to any concerted effort to solve a problem (for example, “war on poverty”).