The only solution is political, give the Russians Crimea and the Donbas and if need be get a demilitarised zone like North and South Korea, removing Putin like this will stir a pile of **** that has far reaching consequences.
So what you're saying then is:
a) Reward Russia for it's aggression
b) Send a signal to the Putin regime that we would rather sue for peace on his terms than fight back.
Surely that's what encouraged Putin in the first place. The knowledge that if we say "this far and no further" it's an empty threat.