The VKS is operating over the frontlines with attack helicopters and Su-25s only.

So, what do you think could, say, stuff like PAC-2/3 Patriot SAMs, or THAADs do - that the already available Ukrainian air defences…

The VKS is operating over the frontlines with attack helicopters and Su-25s only. Su-34s and Su-35s are only sporadically used for deployment of PGMs. Su-27s are flying CAPs. I.e. the mass of the Russian Air-Space Force is not even taking an active part in this war.

So, what do you think could, say, stuff like PAC-2/3 Patriot SAMs, or THAADs do - that the already available Ukrainian air defences couldn't?