Even though plan A (rapid victory) appears to have failed, there is still a rational plan B: carve out the eastern and southern portions Putin wants, leave the rest of the country a smouldering ruin which will cost the west $1tn in aid to rebuild.
A rational plan would've been to confine the conflict into Donbas & Krim. I would make the argument that barely any sanctions would've been put in place if Russia had occupied the areas it was already fighting in, since the west barely cared in 2014
I'm not so sure. If you look at the map, if you want to connect the Krim by land you need more than what was held by the Donbas. That nice wide river coming down from Kiew would make a great border though. And you need something to 'give' in negotiations so you have to take more. Plus Kiew is on that river which would not be great. Would you want Ukraine's capital to basically sit right on your border?
Also I bet you Putin wants these high yield parts, controlling not only Europe's oil and gas supply but also lots of their food supply can only be good for Putin. Look at how much Germany was trying not piss him off even while cruise missiles were destroying Ukraine:
So a little more on the coast too (Odessa). If he does leave some of Ukraine in the hands of Ukrainians to end the war and go back to selling Europe gas and oil then a land locked Ukraine would make much less of a threat later too.
And while we are at it why not try for the whole thing? There's a good plan B there. And if you're gonna threaten WWIII, do it for as much gain as you can.
A trillion dollars of Russian assets have already been frozen by the US alone. Across the whole world, there will be plenty of funds if only a fraction ends up getting confiscated.
