The USSR seemed to spend little or nothing on stealth.
From the book 'Stealth' by Peter Westwick.
Soviet intel and propaganda was always far above what west could do. It is what kept it looking close for two decades.
Korea for example. US could easily use nukes with impunity. It did not but there would be no consequences in terms of nuclear retaliation as Stalin knew what the equation was. Still he took the bet to attack south.. just a mad lad that he was. When Chinese counter attacked if US used nukes again there would be no retaliation, McArthur got retired over that.
I am really happy we lived through that. It is incredibly lucky that it was US that got the nukes first and not Germany or USSR or other similar regime.
If you think "oh this is not so bad" you should watch Threads.
Add to that the effects of medium range Soviet weapons in Western Europe (which they had a lot of) then things would have been very bad here.
Source: The Doomsday Machine: Confessions of a Nuclear War Planner by Daniel Ellsberg
The whole race was about creating nukes to nuke the other nukes out of the orbit when they are attacking, so the total amount of nukes was way beyond what was required to destroy the other side.
I can only speak for Sweden, but a lot of large military and civilian defence bunkers (and hardened, fixed in bedrock artillery) went obsolete went “the other side” got better targeting systems.
Until then, a lot of the installations were immune to anything but a direct hit, which was incredibly unlikely. Airbursts just wouldn’t have cut it to crack open the more serious underground installations.
Just to clarify I meant the old “hit somewhere in the city core” airbursts against which our underground shelters would have held up pretty well. To maximise impact a ground hit is seldom the right choice, too much energy is initially absorbed. (Also the fallout is made worse in a ground burst which can be a bad thing for an attacker if they want to follow up with boots on the ground.)