Yesterday, General Martin Dempsey, Chairman of the Joint Chiefs of Staff, announced an update to the Pentagon playbook on cyber war, the first in seven years. Cyber, the over-broad term for all things online, electronic, and networked, is a relatively new arena in war, though the U.S. military has been grappling with rules for using it since at least the Yugoslavian intervention in 1999. The amount of infrastructure, commerce, vulnerable information, and communication on the internet has increased greatly since then, and the Director of National Intelligence now sees cyber attacks as the leading national security threat facing America.