Here gos the rubbish " Russians has no logistic capability".Its a tough call for the Ukrainians, defend the key lines in the South or go all out to block the new front wherever it may emerge and kiss goodbye to the South forever, or lose another large chunk of the country somewhere.
Say, you establish the point of attack, creating full logistic chain there with trauck convoys, depots and so on.
Effect? It will be obivous for everyone what you plan, and they prepare in advance.
So, you prepare several possible deployment area, each with skeleton logistic systems.
Choose one just at the time of attack, and move every other military unit and logistic structure to the choosen one.
Result ? logistical problems, because you have no chance to extablish the full system prior of need.
Everyone compare this to the typical USA agression, when they select a weak and isolated country, pile of supplies, logistic chain and so on without any consewuence, an when finished in they time and manner doing the invasion.
Say if Russia fight against Serbia or Finland it could be OK, but with a 30+ million country, with a pupet goverment and the USA as puppeteer it is not possible