Comment by jaapz

There is a wikipedia page with a list of NATO "red lines" crossed by putin, look it up

It's a catch-22 anyway. NATO still really wants to de-escalate, but by allowing Putin to cross these red lines they show weakness to a person who values strength. However if they react violently to a crossed red line, they might trigger EU-wide or worldwide war (not necessarily nuclear).

I wouldn't want to be in the shoes of NATO leaders right now