Both statements you quoted can be true at the same time. Russia is the aggressor in this war, and Ukrainian attacks on Russian soil have the goal of repelling the aggressor, and not conquer or subjugate Russia.

If Russia wants to stop these attacks, it can do so at any point. Their government simply has to stop their attacks on Ukraine and retract its troops. Surely, even to a madman like Putin, this humiliation would be preferable to global nuclear armageddon.