Her blast followed a claim by President Putin that Ukraine was one of several “historical territories” that fell out of Russian rule after the collapse of the Soviet Union. He accused Nato of warmongering and defended his siting of more than 100,000 troops near Russia’s border with Ukraine. Ms Truss said yesterday: “I condemn the Kremlin’s aggressive and inflammatory rhetoric. Nato is a defensive alliance and Ukraine continues to show commendable restraint in the face of Russian provocation and aggression.

       “Russia’s military build-ups on the border of Ukraine and in illegally-annexed Crimea are unacceptable.

       “Any Russian incursion would be a massive strategic mistake and would be met with strength, including coordinated sanctions with our allies to impose a severe cost on Russia’s interests and economy. The UK’s support for Ukraine is unwavering.

       “I welcome the fact that Russia has signalled it is willing to enter talks in January. The Russian Government needs to de-escalate its activities and engage in serious discussions.”

       Mr Putin claimed he is protecting ethnic Russians in the Donbass region of Ukraine and accused its Government of “pushing Russians and the Russian-speaking population from their historical territory”.

       He said: “The future of Donbass should be determined by the people who live in Donbass. We see our role as mediators in creating the best conditions for determining the future of

       the people who live in this territory.”