Hang him, or send the tyrant to Saudi Arabia, like Idi Amin.
Then, roughly, Gerasimov agrees to withdraw Russian forces from Ukraine back to the 2014 border and to hold elections in Russia within a year. Some reparations based on future natural gas flows.
Ukraine joins NATO, but NATO agrees not to station troops in Ukraine except in response to an invasion. More of an airspace defensive umbrella than anything.
Rebuild Ukraine.