This is a Russian point of vulnerability:
Much as they may support Putin’s Ukraine policies, Russians don’t want to repeat the experience of suffering mass losses over a conflict in another country. Last year, one state-run poll found that two-thirds of Russians opposed sending troops into Ukraine, while barely more than a quarter of the population supported the idea.
Russia is unwilling to admit their losses of 200-250 killed in Ukraine so far.
As I've written before, Russia can be stopped if a lot more body bags carrying dead Russian soldiers head back to Russia.
Putin himself is willing to suffer more dead Russians to continue his subliminal war:
A Washington-based think tank on international affairs has released a scathing report on Russia's "direct military intervention" in eastern Ukraine, concluding that President Vladimir Putin has led his country into war and lied about it.
The report by the Atlantic Council also charges that Putin is using the decrease in hostilities that has followed a February cease-fire deal to reinforce Russian-backed rebels with troops and weaponry in order "to prepare for the next stage of fighting." ...
The results are what the authors call "irrefutable evidence" that the conflict in eastern Ukraine is "a Kremlin-manufactured war -- fueled by Russian-made military equipment, fought by Russian soldiers, and supported by Mr. Putin."
Russia will continue this war until he gets what he wants--or until the Russian people tire of the casualties. Make more Russian casualties and publicize the dead so the Russians know who is dying.
Who has pain dominance? Russians trying to conquer Ukrainian territory or Ukrainians defending Ukraine's territory and freedom?
Oh, and to add to Putin's pain, allow those Russian soldiers abandoned by their government in Ukraine's custody to relocate to the West (after thorough background checks, of course). And publicize it ahead of time and with leaflet drops of "safe passage" documents to encourage Russians in the next hand puppet offensive to surrender.