The UK needs to have the capability to attack in response to cyber-assaults on critical national infrastructure, according to defence minister Nick Harvey.
"As [military theorist] Clausewitz believed, war is an expression of politics by other means," said Harvey in a speech at Chatham House on Tuesday. "This means we should also be able to prevent, deter, coerce or even intervene in cyber space.... We will need dynamic defences that are able to - first, identify and assess risks - but second trace events to their source and stop them."
Harvey said that he recognised difficulties in attributing the source of cyberattacks, but that attribution was not impossible.
"There are those who argue that in countering cyber threats, conventional concepts will be rendered obsolete. I have some sympathy with that view and we will need to adapt our analysis to the architecture of cyber space," said Harvey. "But, I do not believe we should just concede that because it will be difficult to apply concepts like deterrence to cyber space, that it will be impossible."
One legal basis for retaliating to attack, Nato article V, provides guidance for retaliating to cyber attack, said Harvey.
The Defence Cyber Operations Group, which was announced in the Strategic Defence Security Review in October, will "provide a cadre of experts from across Defence to support our own and allied cyber operations, to secure our vital networks and guide the development of our cyber capabilities," said Harvey.
The group will also be responsible for developing, testing and validating cyber techniques as a complement to traditional military capabilities, said the defence minister.
Cambridge University security technology expert Richard Clayton told ZDNet UK on Wednesday that it was very difficult to attribute cyber attacks, as data can be streamed through a number of proxies. As a consequence, a counterattack may target the wrong country or entity.
"The real problem with cyber attack is you can tell the previous hop, but unless you're lucky, it's hard to tell where an attack came from," said Clayton. "Running down a state and attacking in response is extremely problematic, because you may get the wrong people."