In short, lack of expertise and factories most of which where in Ukraine.
But let’s take a look.
Today’s Russian army is the legacy of the Red Army of the Soviet Union. The Soviet Union was one of the two superpowers of the world during the Cold War and was considered (falsely) the only military rival of the United States.
For this reason, the combat organization, the type of weapons, and in general the military doctrine of Russia was perceived to be based on symmetrical warfare with an army of the same level and rank, and it is optimized for all-round battles, lightning, and with high dynamics and mobility. The doctrine is based on inaccurate information.
In fact, Russian tactics and methods are steeped in old methods proven as failures in the past.
What we have seen is a paper tiger Russian Army. Weak, divided, corrupt and built on false premises.
The military plans that were practiced by the Soviet Red Army were based on scenarios such as a full-scale attack against NATO, a perceived lightning advance on European soil and the destruction of all the infrastructures and offensive and defensive, logistical and industrial capabilities of the European powers. The only way this could be accomplished is through Nuclear War. Many advanced Russian missiles are designed and produced to carry nuclear and atomic warheads. For this reason, the amount of destruction and the explosion radius of these missiles in full-scale war conditions does not justify the costs required for their construction, production, and use. Europe would be a desolate and unusable wasteland. And Russia would suffer worse.
But the campaign in Ukraine is not the kind of full-scale war that was foreseen in the military plans. Outdated plans that could never be fulfilled. Corruption and deceit in Russia is at the core of this failure. Russia was fearful to enter the war in Ukraine, and enter this battle when all knew it was coming. The US use of exposing every Russian move prior to the war, publishing every Russian strategy, unnerved Putin to the point of irrational predictability.
What are Russia’s reasons for entering into war with the aim of completely occupying the territory of Ukraine? Putin needed better ratings at home to ensure a lifetime at the Russian rudder, much like Xi just accomplished in China (as he executes an old-style Communist purge). Russia does not have the capability to occupy all of Ukraine without nuclear war. Such a war would devastate Russia. Putin knows this yet foolishly believed the world would stand idly by as his post-Olympic invasion was defined in the press before its execution.
Was Russia unable to completely occupy Ukraine? Military experts say that of course it could not.
If he had occupied all the territory of Ukraine from the beginning with a full-scale and lightning attack, could Putin not have destroyed the Ukrainian forces with a lower cost by taking advantage of surprise? Putin does not have this strength. NATO intelligence capabilities are too strong for any such surprise. There would be no Color Revolution in Ukraine.
Russia’s calculations were wrong. In the sense that the Russians hoped that with the start of the attack, the Ukrainian government, like the Georgian government in 2007, would quickly reduce its hostile positions and come to the negotiating table. But exactly the opposite of this story happened.
The developments in Ukraine and Russia are much bigger and more complex than military analysts imagine. Ukraine is NATO trained. Russian nihilism rooted in its past creates a psychological blind.
In Russia, there are parks where Russian children and teenagers are taught to play chess and think strategically from an early age. Yet, Ukraine does the same while doing so with modern thinking, flexibilty in movement and continuous adaptation. The Russian chess game in Ukraine was designed to clash with a small, Ukronazi Ukrainian Army. While the small Army is highly trained, skilled, and cognizant of Russian strategies.
The first point here is that at least since 2000, Russia has sought integration and integration with Europe as long as borders return to the Soviet era. A bitter pill too large to swallow. The ideal of a new Eurasian bloc has been at the top of Russia’s strategic plans. For this reason, the Russians invested heavily in the establishment of the Nord Stream 1 and 2 pipelines in order to connect European industries, especially German industries, with Russian energy sources as a method to create subservience. A subservience demonstrated as gas blackmail.
Following the policy of expanding NATO to the East, NATO sought to prevent the return of an Iron Curtain. A return to the invasions of former Eastern Bloc CCCP countries. Putin has been stopped in Ukraine.
Russia could not mobilize all its capacities overnight for a full-scale war with NATO because they do not exists as defined on paper. Nor can they ever hope to win such an engagement. To do so would prove the end of Russia.
Iranian drones are a method to bring Iran into the fold while supplying weapons where no more exist.