Intriguing argument here to the effect that Putin's end of the conflict in Ukraine may be inspired by the work of the late Alexander Solzhenitsyn:
In "Rebuilding Russia," published in the dying days of the U.S.S.R., Solzhenitsyn criticizes the Soviet government's haphazard border policies that he says carved up traditional "Rus." He advocates a "Russian Union" encompassing Ukraine, Belarus, Russia, and the ethnic Russian parts of Kazakhstan,
Solzhenitsyn is confident of the fundamental unity of the Belarusian, Ukrainian, and Russian peoples, three branches that were historically separated by "the Mongol invasion and Polish colonization."
Solzhenitsyn acknowledges the suffering of Ukrainians under the Soviets, but says that is no reason to "hack off Ukraine" and, especially, "those parts that weren't part of old Ukraine...Novorossia or Crimea or Donbas and areas practically to the Caspian Sea." Foreshadowing today's Russian rhetoric, Solzhenitsyn says that, if Ukraine is to be independent, then those regions should be allowed "self-determination."
I still don't think that Putin actually believes in anything, but to the extent a justifying idea becomes necessary, this would certainly do. If he is following this particular playbook, Solzhenitsyn's warning that control of non-Russian peoples dilutes the pure essence of Rus-dom, might indicate the extent of Putin's wider ambitions.
As regards the primal unity of Rus, you can read how that's working out on the ground in Ukraine in this fantastic essay by Keith Gessen from both sides of the war.