The main responsibility for countering this deliberate escalation of armed violence lies, ultimately, with NATO. While the Alliance cannot send troops into the war zone, it can provide effective support to Ukraine for regaining the initiative.
This economic vulnerability leaves Russia in a precarious position where every attempt to exhibit strength transpires as a bluff. NATO is the key addressee of this bluff, and it has to call it by taking it seriously. Poroshenko, meanwhile has had to sort out the complex combination of war and diplomacy. Paradoxical as it may seem, the Russian intervention has been a consequence of the Ukrainian president’s success, and in a way, it makes his task easier. Ukraine no longer has to fight “eastern Ukrainian rebels” while trying to win the hearts and minds of civilians. The Russian army is a formidable enemy, but it can only deploy so many “green men” and unmarked tanks. Putin may boast that he can take Kyiv in two weeks, but he likely knows that he has no chance of prevailing in this confrontation. So the real question is for how long he will be able to hold Moscow.