Firstly, Ukraine is doing everything what they intensively prepared themselves for last 8 years. Their military doctrine was prepared for the conventional war with Russia and Ukrainian generals were aware about the Russian Military Doctrine.
The Russian government did not except such resistance and they operated according to their Soviet military doctrine based on their traditional army model. This military doctrine has a lack of competence, and it explains why Russian had so many unexpected losses in the battles. They hoped for limited and restricted resistance but were trapped in their own worst-case scenario.
Russian Military Doctrine is outdated and not fit for modern purpose, needs change and adapt to new modes of waging warfare, the number of professional officers that was wasted over last three months on the original blunder, makes introduction of effective change neigh to impossible.
Ukraine Is Holding Control Over the Strategic Initiative.
Ukrainian Army absorbed the expected attack and dished out resistance on the Russian Army. Russians regroup in unsatisfied manner and now moved into phase two. Ukrainians organized the controlled tactical retreat in the east and southeast part. They will keep pressure up on Nikolayev and tying up more Russian units from that area.
Certainly, it is not all victorious for Ukraine either, but they have manpower and time to train replacements, equipment, allies and high morale.
Russia Never Had a Chance for Quick Military Victory.
Russia was never going to win this war anyhow, and this war does not even seem to be about Ukraine.
It is increasingly clear that this war was direct result of the Western intelligence services involved in geopolitical power struggle against Russia and Ukraine. The main motivation for the West was the harm against two Slavic nations and bring them down and the cult of their economy. This may have been inspired and instigated indirectly by Western Secret Services themselves, in revenge for Russian-Chinese strategic cooperation. The Western political establishment are vengeful and have long historical memory.
However, Russians maybe well justified to see that plot – misinformation campaign that led to irrational decisions by Vladimir Putin as having deeper roots and involving a lot more peoples then originally have been thought of.
There are many other groups in the West, that have vested interest in masterminding and supporting downfall of stability in the Eurasia reign.
Moreover, it explains quite a lot about such Russian threats as the unseen wider enemy, talk of undermining the security of their state and the hypothetical possibility of the 3rd WW that Russia is already “de facto” fighting.
Russia has hard time to identify what is the source of the situation that is unfolding within the inner clockwork of their sprawling apparatus of state control. Not knowing whether it is externally orchestrated, or home grown, questions like has the cause been removed or just a symptom, keep them guessing. While at the same time, after being provoked by the West, now Russia is trapped in wrong war with wrong people for perhaps geo-strategically right, however totally outdated reasons. All this with no clear opportunity of face-saving way out. President Putin has been trapped. He continues this war in hope that some perspective will come out of it (like Ukrainian will to fight is broken) and they give it up and go home.
Scenario In Which President Putin Loses Control One Way or Another.
Now he will make a choice how his place in global history will be recorded, and to do that, he needs to have time in power, to write it into Russian historical narrative in hope that his legacy will not be entirely tarnished.
In this context: If Ukraine militarily push Russian troops out of the occupied territory, Russia could use threat of tactical nuclear strike. I expect them to use that rhetoric also in case of Crimea as well, however they have no international legitimacy over this area.
If the President Putin can survive internal struggles for the highest power in Russia, then he will easily survive the military defeat because it was a failure of the Russian Army, that now needs to be fast reformed.
Russia will simply lock at home, isolation, and hook up to China, exchange raw materials for products and in 20 years, will be ready with China for next Global conflict. Russia comes back for revenge or Vladimir Putin loses his political power beforehand and the world resets to new turbulent geopolitical dynamic.