Russia declared Nato a major "threat" yesterday after the Western military alliance announced plans to reinforce defences in eastern Europe because of the Kremlin's perceived stoking of war in Ukraine.
Moscow's surprise declaration of a shift in its military doctrine came just ahead of a Nato's summit in Wales tomorrow at which beleaguered Ukrainian President Petro Poroshenko will lobby US President Barack Obama for military support.
Obama will deliver a message of firm Nato support for its newest members from the former Soviet empire when he visits the tiny Baltic state of Estonia today.
Amid escalating tensions, Ukraine's defence minister on Monday said Russia is responsible for bringing a “great war” on Europe and will be responsible for “tens of thousands” of deaths if the crisis escalates.
Russia has consistently denied arming pro-Moscow insurgents, claiming that there has been - and will be - no military intervention.
On yesterday morning, however, its Security Council announced that it would update its “military doctrine by the end of 2014 to reflect Nato expansion”.
It also warned that “military aggression against [Russian-controlled] Crimea will be considered aggression against Russia”.
The developments come after it emerged that Russian President Vladimir Putin reportedly told the outgoing president of the European Commission he could "take Kiev in two weeks”.
According to Italy's La Republica newspaper, Jose Manuel Barroso said that Putin made the comment after the Ukrainian President Petro Poroshenko had left the table at the Nato summit over the weekend during talks on the crisis.
Poroshenko has accused Russia of “direct and undisguised aggression” in the east of Ukraine.
Barroso reportedly said Putin first made the remarks in a telephone conversation held on 29 August, when the Russian president was accused of being responsible for the military action of the separatists in Ukraine.
Putin is reported to have interrupted, saying: “The issue is not this. If I want, I can take Kiev in two weeks”.
However, yesterday morning a Russian official complained that the statement was "quoted out of context and carried a completely different meaning".
Ukraine on Tuesday reported losing 15 more soldiers in the latest day of clashes with Russian-backed insurgents whose ongoing offensive threatens to stamp Moscow's permanent hold on the eastern half of the ex-Soviet state.
Tensions between Russia and the West increased yesterday after it was revealed that Nato will create a 4,000-strong spearhead force in the region with military equipment stockpiled at bases in Eastern Europe.
Its forces will be available within 48 hours should Russia militarily intervene in Ukraine.
Yet the plan would be of no immediate help to Ukraine's government because since the country is not a member of Nato -- a point stressed by Obama in his rejection of calls to involve the US military.
Putin on Sunday hardened Russia's previous position of demanding only talks on autonomy for the region by noting that Kiev would have to discuss "statehood" for the two rebel eastern district.
Meanwhile, European Union governments will decide on a package of new sanctions against Russia by Friday, Italian Foreign Minister Federica Mogherini told the European Parliament yesterday, calling for "the strongest possible response."
Mogherini, who will be the bloc's next foreign policy chief, said the European Commission, the EU executive, will present a strengthened package of sanctions against Russia over its military invasion of Ukraine by Wednesday.
The UN refugee agency, meanwhile, said fighting in Ukraine has driven over half a million people from their homes, warning that the real number could be double.