In the case of any advance of Ukrainian army positions - and who is to say whether there is or not - Ukraine's President Poroshenko says he will declare martial law across his country within hours. As RT reports, Poroshenko added that Ukraine will "demonstrate its readiness for war, for victory, for defense and for peace."

For martial law to be enacted, the parliament has to approve a corresponding ruling by the Ukrainian president. It can be declared in the whole country or selected regions. And as RT reports, 

[Poroshenko]  said he would sign a decree introducing martial law immediately, should there be an offensive against Kiev's army in the east of the country: "My key position: if the ceasefire is broken now, if the line of confrontation is crossed, if an advance against the Ukrainian armed forces is organized, at that very moment I will sign the decree on introducing martial law and pass it to parliament.