The chancellor, speaking amid warnings about Russian-backed hacking, also told enemies that Britain would “retaliate in kind” to attacks, describing this as “the best deterrent”.
“There is no doubt in my mind that the precursor to any future state-on-state conflict would be a campaign of escalating cyber-attacks, to break down our defences and test our resolve before the first shot is fired,” Hammond said. “Kinetic attacks carry huge risk of retaliation and may breach international law.
“But in cyber space those who want to harm us appear to think they can act both scalably and deniably. It is our duty to demonstrate that they cannot act with impunity.
“So we will not only defend ourselves in cyberspace; we will strike back in kind when we are attacked.”
Setting out his National Cyber Security Strategy, Hammond also outlined his business case for heightened defence. If the UK is to become “the best place in the world to be a tech business”, he said, it is “crucial that Britain is a safe place to do digital business”.
Hammond added: “If we do not have the ability to respond in cyberspace to an attack which takes down our power networks leaving us in darkness, or hits our air traffic control system, grounding our planes, we would be left with the impossible choice of turning the other cheek and ignoring the devastating consequences, or resorting to a military response.”