A new British ‘cyber force’ will take down enemy computer systems and hack into enemy air defences to protect our warplanes.
Made up of both military personnel and spies from MI6 and GCHQ, the National Cyber Force will eventually be 3,000-strong.
It will also have teams hacking into terrorists’ mobile phones to stop their plots and into paedophiles’ online chat rooms to destroy their ‘vile material’.
Experts say the force will ‘help to prevent the internet from being used as a global platform for serious crimes, including sexual abuse of children and fraud’.
Defence Secretary Ben Wallace said its budget of £1.5billion over the next four years ‘will give us the capability to launch offensive cyber operations against our adversaries’ in ways not seen before.
Instead of using electromagnetic jamming to protect UK warplanes, Britain would hack into enemy air defences to stop them deploying missiles.
Mr Wallace said the force would also combat organised criminals linked to the Russian state. ‘We need sometimes our ability to deal with that problem,’ he added.
GCHQ director Jeremy Fleming said the force ‘brings together intelligence and defence capabilities to transform the UK’s ability to contest adversaries in cyber space, to protect the country, its people and our way of life’.
And Foreign Secretary Dominic Raab predicted it would become a ‘world-leading force for good, capable of conducting targeted, responsible cyber operations to protect our national security’.
However Mr Johnson hinted the move could come with a future cut in Armed Forces manpower, adding that the best military units would not be the largest but the 'most swiftest and most agile'.
Mr Wallace meanwhile said the focus on recruitment would shift towards the new National Cyber Force in the future.
He added: 'Do I think the Armed Forces will be as big in five years's time as it is now? No, I don't. But what will drive that scale is going to be our equipment requirements and our threat.'
'We shall forward deploy more of our naval assets in the world's most important regions, protecting the shipping lanes that supply our nation,' he told MPs.
Outlining a futuristic vision for the Armed Forces, the PM also said the warships will carry lasers which will make ammunition redundant.
He said: 'Our warships and combat vehicles will carry 'directed energy weapons', destroying targets with inexhaustible lasers and for them the phrase 'out of ammunition' will become redundant.'
Billions of pounds will be poured into a space centre amid soaring threats from Russia and China and also a new cyber centre made up of troops and spies.
The new RAF Space Command will launch British satellites and the country's first rocket from Scotland in 2022.