Complex sentence: As Russia's intervention emboldened the Russophone Ukrainians already in upheaval, the unrest in the Donetsk and Luhansk oblasts devolved into a war between the post-revolutionary Ukrainian government and pro-Russian who were often supported and by the Russian military and its special forces.
Split into simpler sentences: As Russia's intervention emboldened the Russophone Ukrainians already in upheaval, the unrest in the Donetsk and Luhansk oblasts devolved into a war. As the conflict progressed, the Russophone Ukrainian opposition turned into a pro-Russian often supported and by the Russian military and its special forces.