Putin waiting for the ground to freeze
Putin needs the ground frozen hard for his tanks to cross the flatlands into Ukraine. Historically these flat areas were used by previous armies to invade Russia. We are fooling ourselves into thinking that sanctions will stop Putin from invading Ukraine. He already had his mind made up when he positioned 140,000 Russians around the border between Ukraine and Russia. The Russians have a long history of fighting in the frigid winter months. They defeated the German Army using the cold. And Russia defeated Napoleon using the Frigid weather as well.
Russia already invaded Ukraine and annex the Crimea part of Ukraine back in 2014 and NATO did NOTHING. Putin like Hitler sees weakness and will take what he wants until he is met with force that stops him.
Remember that Ukraine is not a member of NATO and we are not obligated to defend Ukraine as a member of NATO. This is why Biden is only sending US Troops to nearby NATO countries to prevent Putin from taking NATO countries like he did with Crimea.