We are making an assumption that Putin really wanted to 'take' all of Ukraine. If the country does not want you, occupation is expensive and possibly not worth it, USSR found that out and maybe Putin learned that lesson. Maybe he just wanted Donbas and Crimea and to bitch slap all the Ukrainian militia on the border with an attempt to end the 8 years of shelling that have been going on at the border.
We are making an assumption that Putin really wanted to 'take' all of Ukraine. If the country does not want you, occupation is expensive and possibly not worth it, USSR found that out and maybe Putin learned that lesson. Maybe he just wanted Donbas and Crimea and to bitch slap all the Ukrainian militia on the border with an attempt to end the 8 years of shelling that have been going on at the border.