I can think of no moral justification for letting Putin pulverize Ukrainian cities which are populated by noncombatant citizens.
On the contrary, heaven and earth will eventually condemn us for standing by as Saul did as others stoned Stephen to death, albeit at an obviously larger scale.
As far as possible, we need to make the skies above Ukraine safe, cut off the Russian supply lines from behind and destroy the tanks that are circling the cities in order to slowly starve their citizens.
All of this would have to authorized by a super majority in the General Assembly of the United Nations.
I understand that we should not simplify complex issues. But working for decades with people who have to make life and death decisions persuades me that there are at least two ways we try to postpone them.
One of them is to say that we need more information. The other is to contend that we need to wait until a complex situation simplifies itself.
It's OK to play these games for a while but not for a long.
Putin....... soon or later we will have to resurrect the Doctrine of "Mutually Assured Destruction" and call his bluff. If we don't do it now, we will have to do it some time in the future. Otherwise, we will for forever be held hostage to his threats.
This is serious stuff and we should treat it seriously.