The main reason they're doing this to create a buffer zone to prevent Russia from bombing their civilians. If the west had allowed Ukraine to use their weapons

The main reason they're doing this to create a buffer zone to prevent Russia from bombing their civilians. If the west had allowed Ukraine to use their weapons on Russian soil they could've used those to accomplish the same, but here we are and they're doing what the can. Another reason is to destabilize Russia and to show the world that Ukraine can fight back.