I think it was 50% underestimating the ferocity of the Ukrainian defense and 50% overestimating the ability of Russia to fight a modern conflict. Combined with

I think it was 50% underestimating the ferocity of the Ukrainian defense and 50% overestimating the ability of Russia to fight a modern conflict. Combined with the rapid influx of modern anti tank missiles, electronic warfare and UAVs prior to the invasion, there were some pretty dramatic changes to Ukraines capabilities to defend itself which Russia has just not responded to very well to. The perception of Russias performance from the rest of the world has been set back decades and will likely take a generation to recover from (if ever). The only thing that keeps the world community from laughing them out of the room is they have a large strategic nuclear arsenal and all it takes is a single launch of those weapons to change the world forever.