General Sir Adrian Bradshaw said Article 5 of the Nato charter – in which an attack on one member state is an attack on all – could apply to unconventional forms of warfare

Russia’s cyber hacking, meddling in elections and fake news could be deemed acts of aggression by Nato, Britain’s most senior officer in the alliance warned yesterday.

General Sir Adrian Bradshaw said Article 5 of the Nato charter – in which an attack on one member state is an attack on all – could apply to unconventional forms of warfare.

His comments signal a possible expansion of the interpretation of the mutual defence guarantee - which means all states in the alliance could decide to strike back.

The deputy supreme allied commander, who is a former director of UK Special Forces, said Nato must step up its defences to deal with the tactics.

He said the West needed a ‘grand strategy’ to counter such threats.

Asked if disinformation and meddling, such as Russia’s alleged interference in the US election came under Article 5, he said: ‘Article 5 is when it’s declared to be Article 5.

‘It is a political decision, but no, it is not out of the question that…blatant aggression, in a domain other than conventional warfare might be deemed to be Article 5.’

Asked if disinformation and meddling, such as Russia’s alleged interference in the US election to help Donald Trump (right) came under Article 5, he said: ‘Article 5 is when it’s declared to be Article 5.' Pictured left: Vladimir Putin in Berlin on October 19

General Bradshaw, who is due to step down from his post this month, helped to oversee a transformation within Nato which saw the alliance focus its efforts to eastern Europe.

In the coming weeks some 800 UK troops will deploy to Estonia as part of the biggest build-up on Russia’s borders since the Cold War.

The build-up is designed to send a message to Moscow. General Bradshaw told the Times: ‘Do not mess with Nato.

‘You set foot in one of these countries… you’re taking on Nato with all that that implies… so woe betide a nation that does that.’

He said failure to respond to ambiguous warfare would increase the risk of military conflict.

He said: ‘This is not just about military deterrence. What we require is hybrid deterrence.

Sir Adrian, pictured here meeting King Philippe of Belgium at the Royal Palace in Brussels, said failure to respond to ambiguous warfare would increase the risk of conflict

‘We require the ability to defend our vital assets from aggression in any area.’

He warned President Vladimir Putin could seek to replicate the unconventional tactics used to destabilise Crimea before its annexation by Moscow in 2014.

The danger, he said, was that the Kremlin would create a situation where it believed it could use its military power to ‘finalise the deal’.

While the risk of a slide into military confrontation between Nato and Russia was small, the consequences if it happened would be ‘catastrophic’.

‘The concern is that by a combination of means Russia gets themselves in a position where they see an opportunity to employ the military arm of power and that could be incredibly dangerous,’ Gen Bradshaw told the BBC.

The danger, Sir Adrian said, was that the Kremlin (seen in this file picture) would create a situation where it believed it could use its military power to ‘finalise the deal’

‘We have seen it in Crimea - a combination of unconventional military and non-military means including cyber warfare, political agitation, economic leverage - where military forces then closed in to finalise the deal.

‘The risk of a slide into a military confrontation with Russia is small - very small - but because the consequences would be catastrophic we have absolutely got to deal with that risk.’

Gen Bradshaw’s comments echo a recent warning by Defence Secretary Sir Michael Fallon that Russia was ‘weaponising misinformation’ in a sustained campaign of destabilisation against the West.

In a speech last month, he accused Moscow of using cyber weaponry to ‘disrupt critical infrastructure and disable democratic machinery’ in a series of attacks on western countries.