THE PRIME Minister has vowed to cripple Russian President Vladimir Putin with sanctions in his televised address to the nation.

Boris Johnson appealed directly to Russian families in the statement at midday, saying he was sure they would not want to be branded a "pariah" alongside their leader.

Mr Johnson said the "Russian dictator" had "just authorised a tidal wave of violence" against Ukraine, and added: "The parents of Russian soldiers who will lose their lives...I cannot believe this is being done in your name or that you really want the pariah status it will bring to the Putin regime."

He also addressed the Ukrainian people, saying that the UK was praying for them and their families "in this moment of agony."

He continued: "We are on your side.

"And if the months ahead are grim, and the flame of freedom burns low, I know that it will blaze bright again in Ukraine because for all his bombs and tanks and missiles I don’t believe that the Russian dictator will ever subdue the national feeling of the Ukrainians and their passionate belief that their country should be free."

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Mr Johnson said he spoke with the Ukrainian president shortly after 4am today, and added: "We – and the world – cannot allow that freedom just to be snuffed out.

"We cannot and will not just look away.

"It is because we have been so alarmed in recent months at the Russian intimidation that the UK became one of the first countries in Europe to send defensive weaponry to help the Ukrainians.

"Other allies have now done the same and we will do what more we can in the days ahead."

He announced there would be a "massive package of economic sanctions designed in time to hobble the Russian economy" and stressed the need to " collectively cease the dependence on Russian oil and gas that for too long has given Putin his grip on western politics."

The Prime Minister continnued: "Our mission is clear. Diplomatically, politically, economically – and eventually, militarily – this hideous and barbaric venture of Vladimir Putin must end in failure."

Just before Mr Johnson's address, head of Nato Jens Stoltenberg said there was no suggestion that members would be sending troops to Ukraine, but added that an attack against any Nato country by Russia would be seen as an attack on them all. 

He said: "Nato’s core task is to protect and defend all allies. There must be no room for miscalculation or misunderstanding.

“An attack on one will be regarded as an attack on all. This is our collective security guarantee.”

He said Nato ambassadors had agreed to activate the alliance’s defence plans, enabling it to deploy forces to where they are needed.

“This is a prudent and defensive step to protect and shield allied nations during this crisis,” he said.

He said there were more than 100 jets at high alert protecting alliance airspace with more than 120 ships at sea, from the High North to the Mediterranean.

“All this shows that our collective defence commitment – Article 5 – is iron clad. We will continue to do everything that is necessary to shield the alliance from aggression,” he said.