The National Security Strategy last year categorised the threat of cyber attack as a tier one risk - the same as terrorism and global instability - so no wonder it is top of the Government's agenda.
The UK will "strike back" if it comes under cyber-attack, Chancellor Philip Hammond will insist as he announces a package of measures aimed at protecting the Government, businesses and citizens from online threats including state-sponsored hackers.
Ministers fear society is increasingly vulnerable to cyber-attack, with the rise in the number of devices linked to the internet potentially giving hackers a soft target.
The new strategy aims at bolstering defences, but also involves significant investment in "taking the fight to those who threaten Britain" through law enforcement and measures to hit back at cyber-attackers, officials said. It is backed by £1.9 billion of funding.
Ministers did not specify which countries pose a cyber threat, but the launch of the strategy follows Russia coming under suspicion about involvement in hacks aimed at Hillary Clinton's US presidential campaign and warnings from the head of MI5 about Moscow's actions.
The new strategy also aims to address concerns about the vulnerability of the so-called "internet of things" - networked devices including household appliances. Experts have warned that many of these devices feature little in the way of security, making them easy targets for hackers, potentially opening a way into networks.
Cabinet Office minister Ben Gummer said: "No longer the stuff of spy thrillers and action movies, cyber-attacks are a reality and they are happening now."
Hammond, who will formally launch the new cyber strategy in a speech in London, will warn how vulnerable society is to online attack thanks to the expanding range of connected devices, the continued use of old IT systems by many organisations in the UK, and the ready availability of hacking tools.