Normally you would think an invading army would prioritize three things:
1. Destroy the country's airforce.
2. Destroy the country's air defence systems.
3. Cut off all reinforcement routes.
This is not rocket science and even an armchair general like me knows this.
1. Preferably on the ground.
2. There is a difference between SEAD and DEAD. The 'S' stands for 'Suppression' and the 'D' stands for 'Destruction'.
Each air defense unit is composed of two major units: radar and launcher. And usually they are
PHYSICALLY apart, from a couple hundred meters to kms.
A SEAD package usually accompanies other strike packages and the primary intent is to prevent the air defense radar from transmitting, hence the word 'suppress'. If the air defense radar do not transmit, the entire air defense unit is
TEMPORARILY useless. On the other hand, a DEAD package is often a standalone sortie and their intention is to actually destroy both the air defense radar and the air defense missile launcher. This is a
PERMANENT solution against air defense.
The two concepts overlaps in execution. If something is destroyed, then it is permanently suppressed. So if we can at least kill the radar, then we will at least try. But for the moment, the SEAD priority is to create an air corridor for the main strike package to do its job.
For unknown reasons at this time, the VKS have been undeniably incompetent at S/DEAD against Ukrainian air defense. We do not know if this is planning problem, a human problem, both, or just outright shiddy leadership.
3. Am Air Force, not an Army guy. But I would guess that reinforcement is not available to Ukraine so this is not a major problem for the VKS.
Overall, there seems to be a difference of airpower philosophy between the US and Russia. The US, after the Vietnam War, determined that no strike package will be without SEAD support.
So why didn't Russia do this?
My opinion is that Poutine got bad advice from his generals. Not only Poutine but also Xi Jinping since they are in on this invasion. The fact that China so quickly moved to declare some financial support for Russia indicate that Xi knew what Poutine planned for Ukraine and that Xi consulted with his generals as to the viability of the Ukraine invasion. Did Xi told Poutine that the PLA believe the Ukraine invasion would be a quick success? We may never know.