Russian officials say the Russia-Ukraine conflict is now entering its most dangerous phase. (Photo:TASS)

The two and a half year Ukraine conflict has triggered the biggest confrontation between Russia and the West since the depths of the Cold War, and Russian officials say the conflict is now entering its most dangerous phase.

Russia has been signaling to the United States and its allies for weeks that if they give permission to Ukraine to strike deep into Russian territory with Western-supplied missiles, then Moscow will consider it a major escalation.

Putin said that Western approval for such a step would mean the direct involvement of NATO countries, the United States and European countries in the conflict in Ukraine because NATO military infrastructure and personnel would have to be involved in the targeting and firing of the missiles.

He said that it was too early to say exactly how Russia would react to such a move but that Moscow would have to respond accordingly and different options were being examined.