Putin's theory of sovereignty is that of what Morgenthau called a "Nietzschean foreign policy", a pure power movement that will not stop on its own, satisfied with any set goals. It will keep going until there is clear opposition, until someone stops it.
Yesterday Putin clearly described his understanding of sovereignty: it is the right to the absolute external and internal self-will of the state. Anything that holds it back on the path of expansion limits this sovereignty, turning the country into a "colony".