Twhat we should do is to respond proportionately and to both deter and prevent escalation, with clear statements what we are doing and why.
Wrong...wrong....wrong. And even if you were correct, it's totally irrelevant. There hasn't been proportionality since the first hour of the invasion. Russian troops are in Ukraine (bout 200K at this point), ZERO Nato troops are in Ukraine. The Russian air force dominates in Ukraine, there is ZERO Nato planes in Ukraine. The Russian forces are using cruise missiles, thermobaric rocket launchers, long range artillery, and many tanks...NATO is providing NONE.
A "proportional response" would be NOT LESS THAN, sending in the aircraft, cruise missiles, tanks, artillery, drones, AA systems and conventional weapons of major destruction (thermobaric, cluster bombs, etc.) to supplement and redress Ukraine's significant material and manpower inequality.
AND NO, in war a proportional response is childish thinking. As Putin and Russia and China knows, the object of war is to win. And to win, it minimally requires a disproportion in military power.
The proper response has always been obvious to those without jello'd knees and clay feet.
1) From the outset he allies should have decided what they are willing to do REGARDLESS of the military circumstance in Ukraine. In this case it was everything short of boots on the ground.
2) You don't wait for the enemy to act, YOU DO IT. Your only "escalation" is a single act: maximum sanctions, maximum military aide, maximum political pressure.
3) If after a period of time it does not break the enemy you either withdraw or keep a stalemate.
What you don't do is what is now an apparent and unnecessary blood bath in "fighting by little steps". HOW STUPID IS THAT?