The UK Chancellor has warned of an increased risk of cyber attacks while laying out plans for a previously announced £1.9bn cybersecurity strategy.
Philip Hammond said the country must be able to retaliate against cyber-attacks, adding that "foreign actors" could sabotage the UK's electrical grid and airports.
Decribing the National Cyber Security Strategy in London, Mr hammond said (via BBC News): "If we do not have the ability to respond in cyberspace to an attack which takes down our power network - 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, ignoring the devastating consequences, or resorting to a military response."
"That is a choice we do not want to face and a choice we do not want to leave as a legacy to our successors."
It follows an MI5 warning that Russia poses an increased cyber-threat, which comes after the country has come under suspicion for hacks aimed at Hillary Clinton's US presidential campaign.
MI5 Director General, Andrew Parker, told the Guardian: "[Russia] is using its whole range of state organs and powers to push its foreign policy abroad in increasingly aggressive ways - involving propaganda, espionage, subversion and cyber-attacks."
The Kremlin denies the allegations, with a spokesman saying the Russian governement considers them "unfounded and groundless."
Mr Hammond, who did not refer to Russia, or any other country in his remarks, added: "Our new strategy, underpinned by £1.9 billion of support over five years and excellent partnerships with industry and academia, will allow us to take even greater steps to defend ourselves in cyber-space and to strike back when we are attacked."
The new security strategy will enlarge specialist police units tasked with taking on online gangs, while some cash will be used to fund education and training of cybersecurity experts.
Funded until 2020, the programme will also see more than 50 specialists recruited to work at the cybercrime unit at the National Crime Agency.
It will also create a Cyber Security Research Institute aimed at co-ordinating research among a 'virtual network of UK universities' to improve defences for smartphones, laptops and tablets.
