Ukraine's government says a new convoy of Russian tanks and trucks—some 60 vehicles in all—crossed over the border between the two countries on Thursday, raising fears of a new wave of fighting in the eastern regions of the country.

The incursion, which has not been independently confirmed by journalists in the area, is just the latest sign that the September ceasefire deal between Kiev and the separatists is done. Not that it was that effective to begin with. Sporadic fighting never really stopped in the disputed regions of Donetsk and Luhansk, with hundreds of fighters and civilians being killed. On Wednesday, two teenagers were killed when a shell hit the playing field outside their school.

On Sunday, separatists held parliamentary elections for their self-proclaimed republics, although no international body recognized the results, which the White House called "illegitimate." Officials in Kiev called the elections themselves a provocation and a violation of that ceasefire agreement. As a result, President Petro Poroshenko withdrew an offer for increased autonomy in the region.

If the reports of the new Russian tanks and fighters on Ukrainian soil prove to be true, it could lead to another escalation, or at the very least show that an end to the crisis is nowhere in sight. More than 4,000 people have been killed in fighting there since April.