When western leaders talk about national security, they tend to focus on issues such as the threat from jihadism or the need for capable armed forces. But the US and UK governments are increasingly concerned by what they deem to be one of the 21st century’s biggest security risks: the threat of cyber attacks. Both governments recognise that the digital revolution is one of the prime drivers of global economic growth. But they worry that the internet is becoming an increasingly powerful instrument in the hands of those who want to steal, terrorise and wage war using novel methods.

The UK on Thursday published its first national strategy on cyber security, following a similar move last month by President Barack Obama. Both governments are right to throw a spotlight on this issue. There is increasing evidence that the internet is being used by states as an instrument of aggression. In 2007, Estonia blamed the Kremlin for instigating a wave of cyber-attacks against the Baltic nation. Last year, as Russian tanks moved into Georgia, cyber attacks crippled Georgian government websites. Al-Qaeda and other terrorist groups speak of their wish to wage cyber terrorism on the west. As Mr Obama puts it, a few ­keystrokes on the computer can now become a “weapon of mass disruption”.