I listened to a very interesting lecture from Italian historian Alessandro Barbero about how the world descended to WW2 from a political perspective. Its staggering how similar the situation was to what we have now.
A-You have a country who had just lost land (Germany-WW1 and Russia-Soviet union) and whose quite nationalist driven
B- You have a complacent Western Europe who is in no mood for war and who needs this rogue nation (ie Nazi Germany/Russia) as a bulwark against communism/because it needs its natural resources
C- Similarly to Hitler, Putin is persuading minorities within foreign countries to cause unrest. Any reaction against them is then used as a casus belli to invade and assimilate those countries.
D- similarly to the Nazi army at the beginning of the war, the Russian army is overrated.
E- Putin has an 'italy' in Belarus aka an ally bound by ideology who is being dragged into a war it simply isn't keen or prepared war