No this is just totally untrue. There was definitely some support given but the bulk of the secessionists were the people of Donetsk and Luhansk.

You have fallen for the trick that the Ukrainian government often pulls by calling ALL the people of Donetsk and Luhansk Russians. They no longer call them Ukrainians. And that's the problem, they have firmly stated their intention to kill all of them, they do not consider them Ukrainian anymore and taking back the land means cleansing it of the Russian ethnicity population.