Ukraine uses the S-300.
With Russia, the S-400 has replaced it putting their remaining S-300s into reserve units.
Everything we hear about Ukraine and S-300s comes FROM Ukraine. So when the Ukrainians say that the Russians are now using a surface to air missile (with a small 150kg warhead....and relatively short range) as an ad hoc ballistic missile by simply attaching a 'GPS unit', it sets off my BS detector, alright. The S-300 requires multiple support vehicles just to shoot. The SAM itself is very expensive per round. Why do that when one has plenty...thousands...of dirt cheap reserve Scuds just waiting to be fueled-up and launched? Those have HUGE warheads and very long range.
Ukraine is shooting-off the S-300s in this fight. Lots of them. They have aircraft to shoot down. Russia...not so much if any at this point. The Ukrainian air force is essentially non-existent. A tiny fraction of all the S-300s being fired will actually hit a Russian aircraft. The rest will impact onto Ukrainian territory...or Polish as we've seen.
S-300s impacting onto civilian targets we can assume is the problem here...bad for moral when your own forces are killing the civilians they're supposed to be protecting. So invent an outwardly plausible story about the Russians doing the shooting...only a few missile junkies like DOP will go "Huh??? No way!"
I'll believe it...literally...when I see it in action. ATM all we have is Ukraine claiming it...and they want money.