And how was this decapitation attack on Kiev, a city with close to 3.5 million people, going to happen with the troops the Russians sent there? Are you telling me one unit of VDV would do it? Why bother having large standing armies then? You just send Rambo in a tin can air transportable vehicle and he'll take on the whole Ukrainian army. At best I could see an argument about it being a probing attack in multiple directions and then a pullback and strike on the weaker positions. But that is not what happened is it. They had already bypassed and totally surrounded Chernigov. They already held most of the north of Kiev. So why did they pull back, and send all their troops towards Izium, the place which was actually the one with the greatest resistance? Not Kiev. Izium and Sumy were the places which were holding their attack the best. In the Kiev area they relatively easily entered the towns around Kiev they wanted to at will even with the light armor. The problem would have been going into Kiev with just those units. Kiev is just too big. If you wanted to do an early attack on it, you couldn't spread your troops like they did. And if attacking Kiev was the main objective there wouldn't have been any need to go into Zaporizhzhia at all. Why bother driving all over Ukraine across its whole length all the way from Crimea when Kiev is right next to the Belarussian border? Makes zero sense.
I think the Russians just had the following objectives. Connect Donbass to Crimea, deny Ukraine use of its ports, possibly a defeat in detail of Ukrainian forces in the field. And maybe if they haven't achieved their objectives even then that is when they will start going for other larger objectives like taking the largest cities. And if they do that Odessa and Kharkiv, as cities in the Russian ethnic areas, are the most likely initial objectives. Not Kiev. The fact they regrouped to attack at the strongest resistance point, to me, tells me they are aiming for destruction of the Ukrainian army. i.e. the demilitarization bit announced as a mission objective when this all started. That is ahead of conquering cities.
My read is Russia clearly grossly underestimated the capabilities of Ukrainian forces on the path to Kyiv and the strength of Ukrainian forces available to defend key government centers in Kyiv if it is attacked, as well as grossly underestimated the cohesion and resolve of Ukrainian forces once war has started.
Russia clearly believed Ukrainian forces on the path to Kyiv can be effectively neutralized or at least fixed by the Russian forces involved in the main thrust towards Kyiv, so they can neither greatly hinder the Russian land advance nor retreat into Kyiv to strengthen the advantageous built up defensive positions. They also clearly believed that within a few days after the start of hostility, the forces available to defend inner part of Kyiv would amount to no more than the equivalent of perhaps few battalions worth of light regular troops, that could be overcomes with an sustained assault by elite helicopter or airborne troops operating from a nearby captured and secured air field.
This is why they mounted an early airborne special forces assault on airfields near Kyiv. The intention is to be able to used the airfields as a staging area to shuttle airborne forces into Kyiv starting perhaps with 24-48 hours of start of hostility, while the land based forces make rapid progress to open up lane corridor to the airport, and then from there link up with parachute troops already established in center of Kyiv and occupied the government quarters.
Perhaps Russia believed that was the actual total strength and capabilities of the Ukrainian forces in each of these roles, or the Russians believed there would be enough defections after the start of the hostilities that the effective strength of the Ukrainian forces they would encounter at each place will be very weak.
Given the classical military dictum that effective military offensive against determined enemy requires a 3:1 advantage to succeed, and Russia attacked without even having numerical parity, Russia clearly counted on many things all going in its favor. These undoubted includes:
1. Most Ukrainian forces are ineffective so doesn’t count anywhere close to being 1 to 1 match with Russian forces
2. Ukraine does not have stomach or the capacity to mount a determined urban defence in Kyiv even against a fast but moderate attack by comparatively lightly armed airborne forces
3. In the field the Ukrainian forces not only can not maneuver operationally, but can’t really even maneuver tactically, when attacked by fast moving Russian forces
And possibly, 4. Most Ukrainian forces won’t fight or may even join the Russians.
Incidentally, I see many posters on this forum who make the same assumptions about forces in Taiwan that may oppose a Chinese attack, and some get very defensive and even crossed if these assumptions are challenged.