Day after day, Russia is pounding the Donbas region of Ukraine with relentless artillery and air raids, making slow but steady progress to seize the industrial heartland of its neighbor. With the conflict now in its fourth month, it’s a high-stakes campaign that could dictate the course of the entire war. If Russia prevails in the battle of Donbas, it will mean that Ukraine loses not only land but perhaps the bulk of its most capable military forces, opening the way for Moscow to grab more territory and dictate its terms to Kyiv. A Russian failure could lay the grounds for a Ukrainian counteroffensive — and possibly lead to political upheaval for the Kremlin.