Soviet Union returns (RAR)

[K. A. Pital]

The only treaty that is no longer in effect is the 1972 ABM treaty. The Partial Test Ban Treaty, the Threshold Test Ban Treaty, and the Outer Space Treaty are still in effect. I'd have to look at the expiration date for SALT, but SALT 1 is certainly recognized, and US forces are bellow SALT 2 levels.

Yes, that's right. But if these treaties are all in effect, then it seems little would change for the Soviet/West relationship, except the USSR would be weaker. On the other hand, revisionist China would suddenly get a neighboring state that has a peak Cold War era nuclear arsenal as deterrent and is baseline-hostile to the West. It took decades of NATO expansion into Eastern Europe before Putin chose to side with China. For the USSR, the choice might be just as obvious - China or destruction.

That generation of Russian submarines are nothing but targets to modern Western ones. They and the Russian airforce would only remain relevant due to volume. As was already said though, quantity has a quality all its own. Even if a detected Russian submarine is an automatically dead one, we have far fewer SSNs to track them down too.

Thank god you at least understand the problem with your statement. SSBNs which can operate in polar waters and launch 20 missiles in one go after breaking through several meters of ice, regardless of which generation - but it's the third one, which is a serious capacity for any nation that's building up a credible deterrent - are a serious weapon. Submarines do not fight submarines. The primary attack weapon are ballistic missiles which are meant to wipe out enemy cities. So unless you've got a horde of ASW craft capable of sweeping the entirety of polar waters to find a needle in the hay, I have bad news for you - retaliation will most likely come.

If the Russians are smart they would considerably downsize their largely obsolete navy and airforce immediately and pour their resources into their still relevant and largely invulnerable ICBMs while upgrading their army as fast as possible. That gives them the security of nuclear protection and a bulwark against invasion.

Of course everything needs to be downsized. However, here you are wrong. ICBMs are not invulnerable, their fixed-positions make them vulnerable to a brutal first-strike strategy. Especially with the advent of stealth, which the USSR would no doubt find out just by looking at the shape of foreign airplanes. On the other hand, the aerial, naval and wheel- and rail-mobile deterrent are a mobile, and therefore harder-to-destroy launch point. Unpredictability of positioning makes aerial and naval deterrent credible and important. "Obsolete" for strategic bombers simply doesn't work. B-52 and Tu-95 serve until this day.

In 1979 what portion of the quantity and quality of the Red Army was outside the borders of the USSR? I assume in this scenario all of those troops were lost. If the Red Army is gutted in both numbers and effectiveness can the USSR be maintained internally?

If that's pre-Afghanistan, a lot of forces are deployed in the USSR proper. However, the group of Soviet forces in Germany and E. Europe is lost, along with all the hardware. But the Soviet Army (there's no Red Army at this stage) in any case had a vast pool of reserves and maintained a WARPAC-NATO manpower parity, which was no easy task. Suffice to say there'll be enough troops for internal policing, if need be, but the Army was very rarely deployed for such needs. But since the OP specified the GSFG's return into the USSR, this means we have our most modern hardware and best troops as well.

How would they react to modern China? Will they see the PRC as new useful ally after they found out the numerous trade deals modern Russia did with China, how Putin thanked China (and India as well) for keeping quiet regards to Crimea and that they share some common geopolitical interests. Or will they react negatively to the country from their perspective who only 10 years ago fought a border conflict with them?

See above. If they survive long enough to realize the political climate in the world, and that the West would stop at nothing save nuclear war to kill the Soviet Union, as it was in reality, they'll probably start rapproachment with China much like Putin. Maybe even faster and harder.