The Russia-Ukraine crisis could be days from exploding into war, it is feared.
UK senior commanders and Whitehall officials are on “high alert” and monitoring the situation “with growing concern”, a source told the Mirror.
Moscow has amassed close to 100,000 troops at the flashpoint border and senior Ukraine military sources fear its war-planners may have wrong-footed them.
Putin’s navy on Thursday piled on further pressure on embattled Kiev by announcing the deployment of a war-fighting fleet towards Ukraine arriving within days.
A source said: “Aggressive Russian troop movements towards the border have caused a great deal of concern within the Ministry of Defence.
“The situation is being monitored constantly. I would definitely describe this as a growing crisis.”