All this talk about encircling Ukrainian forces and taking ground would have made sense if the Russians had additional echelons to continue the rapid advance wh

All this talk about encircling Ukrainian forces and taking ground would have made sense if the Russians had additional echelons to continue the rapid advance while the first one sieges. Without a second and third echelon the first one will simply have larger and more vulnerable flanks if they encircle cities. But they have only one echelon which didn't get any objectives. Given the bad logistics and attrition it needs to take the cities or the war is lost. And even if they take the cities the subsequent insurgency can still kick them out of the country. Putin simply did not bring enough troops, hoping that either Ukraine would collapse or that the expensive weaponry (cruise missiles, jets, attack helicopters, modernized tanks) would be much more effective than it is. Soviet doctrine talks about requiring 3:1 or even 5:1 advantage against entrenched adversaries, but they have brought about parity, with Ukraine rapidly getting more volunteers and Western gear in the defensible cities.