The recent rumours about S-300 area defence surface-to air missiles of Russian design and manufacture reinforce my impression that this long-range and apparently respected air defence system has become one of the main deterrents against interventionist Western powers with nuclear weapons, the combination of friendly relations + oil wealth and 'allied' status being the others. Ballistic missiles and chemical weapons proved to possess a rather negative deterrence value.
The S-300 versions of 1984 and later (not the 1978 version) are apparently quite highly respected in part because they weren't yet demolished by a SEAD campaign, unlike the 1960's generation.
The nominal range is large enough to nominally out-range typical anti-radar missiles and to provide at least nominal missile range (not necessarily radar range) for coverage of large swaths of a country.
(The newer S-400 missile with its active radar guidance and and comparable ranges is actually more impressive - maybe it will play the deterrence role in the 2020's? Tactically, the longest ranged S-400 version and similar missiles (if they exist) are hugely interesting, for their range allows the participation of surface-to-air missiles in the offensive air superiority fight. The would also push back airborne early warning and control aircraft as well as long-range radar aircraft such as the E-8. Such 300+ kilometre aerial sensors would then be reduces in range to the forward line of own troops (if such a thing exists) rather than being able to support by looking deep into hostile territory.)
The dynamics regarding the S-300 appear to resemble the dynamics regarding nukes in part: There is a sense of urgency to strike before the deterrent is operational. This adds an actually intervention-/aggression-provoking element to this deterrent.
I think it's sad that such a largely defensive system achieved such a fame and importance. It doesn't reflect well on the West.