Vladimir Putin is gearing up for a 'hot war' he doesn't want - but will not back down if he provoked over Syria, Britain's former ambassador to Moscow has warned.

Sir Anthony Brenton insists relations between the Kremlin and the West are 'the most dangerous' he has ever seen amid heightened tensions over the country's bombing campaign in Syria.

While Russia 'means business' having sent warships past British shores and displayed its military might, Moscow is 'weak' and does not want a war, Sir Anthony said.

Vladimir Putin (pictured) is gearing up for a 'hot war' he doesn't really want - will not back down in a face-off with the West because the humiliation will topple him, Britain's former ambassador to Moscow has warned

In an exclusive opinion piece for the Daily Mirror, he said it is 'close to impossible' for Russia to back down because the ' loss of face would almost certainly be the end of Putin'.

There has been weeks of posturing between Russia and the West with both sides trading accusations over the brutal civil war in Syria.

Today Russia sent the naval destroyer Smetlivy to Syria to join its fleet their for the coming months.

The heavily armed ship left the Crimean port of Sevastopol to great fanfare en route to Syria via Greece to take part in a festival.

And Sir Anthony added: 'If we act on Syria in any way that could escalate to a Russian attack, they are signalling as clearly as they can that they would retaliate.'

Britain's Foreign Secretary Boris Johnson condemned airstrikes on a Syrian school (pictured) that left at least 22 children and six teachers dead

While Russia 'means business' having sent warships past British shores and displayed its military might, Moscow is 'weak' and does not want a war, Sir Anthony Brenton said. Russian troops are pictured in the Novosibirsk region of Russia earlier this month

However, he said that while the situation was dangerous, Russia is also 'weak', spending far less on its military than the West.

He added: 'They do not want war. They would lose. These shows of strength are not an intention to fight, but a signal that fighting must be avoided.'

Sir Anthony, who was British ambassador to Moscow between 2004 and 2008, suggested Russia and the West needed to respect each other's 'vital interests' and said the two parties had managed to pull back from disaster during the Cold War.

Britain this week announced plans to send 800 troops to Estonia at its border with Russia.

Sir Anthony Brenton (pictured) insists relations between the Kremlin and the West are 'the most dangerous' he has ever seen amid heightened tensions over the country's bombing campaign in Syria

More than 200,000 specialists of rescue units and 50,000 units of equipment were said to have been involved in a mass nuclear war readiness drill in Russia

The Royal Navy was placed on red alert after it emerged Russia was sailing a fleet of warships along the British coast en route to Syria

But Sir Anthony said Russia would not attack a Nato country deliberately because 'they would lose'.

While the situation is 'dicey', 'peace still lies in our hands', he said.

Meanwhile, Britain's Foreign Secretary Boris Johnson condemned airstrikes on a Syrian school that left at least 22 children and six teachers dead.

He wrote on Twitter: '[The] world will be sickened by Syrian school bombing. 20+ children dead. Russia and Syria regime must end butchery and agree to peaceful solution.'

International development secretary Priti Patel said: ‘Schools should be safe places to learn, not transformed into places of slaughter.

‘These airstrikes are a barbaric assault on the world's humanity. It is time the Syrian regime, and their Russian backers end this conflict.'

Russia denied involvement in the deadly bombing.

His comments come as Putin accused the West of building up a 'mythical and made-up' threat of Russian aggression to justify increasing military spending and bolstering NATO forces in countries neighbouring Russia.

Putin dismissed claims he is planning to invade another country calling warnings of a new Cold War 'stupid' and 'unrealistic'

RAF personnel are among a 600-strong training group at Lechfield Air Base in Bavaria working with others from France, Spain, Belgium, Germany, the Netherlands and Italy

'It's very pleasant and profitable to make yourself out to be defendants of civilisation from some new barbarians, but the thing is Russia doesn't plan to attack anyone,' he said.

'It's unthinkable - simply stupid and unrealistic,' he added. 'It's just funny to talk about it.'

His remarks come after a spell of increased aggression, which has included unveiling a new super-nuke capable of obliterating an area the size of Russia.

Putin also sailed warships through the English Channel ahead of a fresh offensive in Syria and last night it emerged Russia had launched a new super stealth submarine.

The Veliky Novgorod is the latest addition to the Black Sea fleet and is capable of striking land, sea and underwater targets.

Video has also emerged of elite Russian soldiers who can parachute out of a plane before using special equipment to plunge 30m below water with underwater submachine guns.

Earlier this week, footage showed Russia carrying out a nuclear war readiness exercise involving 40 million of its citizens while 130 military centres have been put on high alert for drills on the region's ability to respond to attacks from the West.

Meanwhile, RAF personnel are among a 600-strong training group at Lechfield Air Base in Bavaria working with others from France, Spain, Belgium, Germany, the Netherlands and Italy.

Russia has unveiled chilling pictures of its largest ever nuclear missile, capable of destroying an area the size of France. A contract for the weapons was signed in 2011, and they are expected to be ready in 2018

Each missile contains 16 nuclear warheads, according to pictures revealed online from the Makeyev Rocket Design Bureau. It is also able to evade radar.

The European Air Group members are working with Norway to test their readiness to deploy as a multi-national task force.

It comes as Russia's military escalation on Europe's border triggered the West's biggest show of force in the region since the Cold War.

However, in Germany members of 34 Squadron RAF Regiment carried out Air Traffic Operations and Force Protection exercises alongside forces from other nations.

The US is also hoping for European nations to fill four battle groups of some 4,000 troops as part of Nato's response to Russia. More troops will be sent to the Baltic states and eastern Poland early next year. They will be backed by Nato's 40,000-strong rapid reaction force.