Cyber-warfare is all well and civilized when it's confined to a tit-for-tat hacking of banks, but it's got the potential to spiral out of control real fast. To try and prevent that, and save the world from a hacked-WoW-account-induced apocalypse, NATO's comissioned a set of international laws to try and make cyber-warfare more…civilized.
Despite how it might seem, war's actually relatively civilized. Agreements like the Geneva Conventions and Ottowa Treaty lay down laws as to how warfare should be conducted - be nice to your prisoners and no blowing people up with landmines, for example - and the UN charter explains when war might be justified, say for self-defence. But none of those were written with cyber-warfare in mind, which is difficult when the Americans are going round hacking the Iranians, the Koreans are hacking each other and China's just hacking everyone.
In an attempt to make some sense of the mess, NATO (basically the Western powers-that-be) commissioned a report from a bunch of legal experts at the ‘NATO Cyber Defence Centre of Excellence' to suggest some rules for cyber-warfare. Well, the report's in, and the suggestions are kinda surprising.
Basically, cyber attacks which cause "physical damage, injury or death" constitute a ‘use of force', and thus can be retaliated to with real physical weapons. Equally surprising is the classification of civilian hacktivists as legitimate targets during war.