That’s a hell of an expensive way to do SEAD. I don’t think they’re using million+ $ cruise missiles to just get the Ukrainians to use up their interceptor stocks. Anyway, they will just be equipped with new western designs like Patriot as they use up their old Soviet stocks. The only reasonable way this could be done is if the Russian have a large amount of old missiles that will soon be decommissioned.
That’s what happens when you cheap out on critical, but less ‘sexy’ support assets and training to afford the big toys. It also doesn’t help that Russia is too weak to play hardball with NATO, so NATO ISR directly taking over key parts of the kill chain for Ukraine makes conventional SEAD effectively impossible.
Thus the only way Russia can currently perform SEAD is by trying to deplete Ukrainian AD missile inventories, while also doing DEAD when they can by using lancets and other suicide drones.
It’s messy, expensive and inefficient, but it’s the best Russia can do in their current situation. The alternative is that the VKS continue to set the war out. In that context, spending a few billion to unlock the fighting potential of hundreds of billions worth of combat assets is a good deal for the Russians.
All the recent air strikes would not have been possible, or at least would have involved far higher risks and likely costs without all the degradation of Ukrainians AD that was achieved due to all the infrastructure strikes beforehand.
Both sides have often reported that the Russians are using S-300s in land-attack mode. My guess is that they’re using up old 5V55s by launching them and forcing the Ukrainians to try to shoot them down. The same cost benefit analysis doesn’t apply to these missiles as they’ve long been out of production and will have to be retired anyway.
Maybe to start with, but software updates will allow NATO ISR to filter out such obvious decoys.
The last point I want to make is that the campaign against electricity hasn’t worked out very well, much like the attacks against fuel depots earlier into the war. In both cases, when capacity goes down the Ukrainians just shift supplies to the military at the expense of civilians (remember the long gas lines early in the war). That’s why the strikes don’t affect Ukrainian rail logistics that much and in case they have no other choice, they could just fall back on diesel trains. Using their missiles on actual significant targets like the Dnieper bridges probably would’ve been more fruitful (and they had enough to do that).
This is why attacking infrastructure is not the primary objective of these missile attacks.