Welcome to the SB Louis!
First of all, I have to say that I'd be extremely
grateful if You try to use capital letters in geographical names bit more often (preferably: always in the first letter). Space between last letter of a word and a comma or period is not necessary as well.
Secondly, this AU's backstory is... peculiar, so to speak.
In 1985, the Soviet Union, in crisis, attempt to cease territories hoping to accumulate enough resources to prevent a collapse
Not sure about that "ceasing" territories, but I assume You refer to expansion. As for accumulation of resources - in terms of natural resources the USSR was probably most resource-rich country in the World. Problem was with their use (and it was a structural problem).
...she annex most of Warsaw Pact members...
Simply annex? Just like that? And they let themselves be simply annexed? In 1986?
...and launch a surprise attack against NATO...
I'm not sure if that would be such a surprise after all these annexations.
While their military is outdated...
In mid-1980s Soviet Union had World's largest standing army, with equipment of varied vintage, but the 1st and 2nd line units in western military districts and in Groups of Soviet Forces (in WarPac countries) were modern enough. NATO forces weren't all M1's and Leo2's either.
...thousands of soviet tanks, right at the borders could storm France in few days and take Paris too fast for an efficient retaliation...
In which case France would press the red button. Matter of, say, 10 minutes. No tank is that fast
The United States Navy, the only hope for a large scale troops displacement is threatened, the Atlantic Ocean is filled with Russian submarines, it's not worth it.
Word "deployment" would be better than "displacement", I believe.
Dealing with Soviet submarines was raison d'être of the US Atlantic Fleet. That's what they trained for for whole 40 years.
...soviet union deploy half of it's troops in europe toward china in an attempt to end the invasion...
In mid-1980s real-life Soviet Army had around 200 tank and motor-rifle divisions, of which 50+ were deployed on China borders and ca. 90 within Western and South-Western Strategic Directions (Baltic, Belarussian, Carpatian, Kiev, Odessa Military Districts; Northern, Central, Southern and German Groups of Forces). Whole French Army had less than 15 small divisions. And what other countries were to seize the opportunity, if the West Germans and Italians are already annexed and US Army is out, supposedly prevented from delivering reinforcements (to those 5 divisions already in Europe) by all these Soviet submarines in the Atlantic?
...China launch a small nuclear attack against Russia, wiping Moscow, the Soviet government and the Soviet army, and destroying the dead hand of Moscow . preventing a soviet retaliation.
Yeah, very small attack indeed. Just some 10 million casualties.
But You are
aware that Soviet Armed Forces weren't located only in Moscow? And that once any
hostilities begun, their command structures would leave their peacetime quarters precisely
to avoid such situation happening?
And finally, the Dead Hand (15E601 Perimetr) system is - for exactly the same reason - NOT located in Moscow and it's organizational design - whatever it is - by definition makes it impossible to destroy it in such way to prevent a retaliation (otherwise, why it would be made in the first place?).
NATO condemn chinese attack and cease all relations with China.
So, You're saying, that NATO was attacked by Soviet Union, but when Soviet Union is in turn attacked by China, the NATO "seizes the opportunity" to strike back at USSR, while at the same time it condemns China for providing that opportunity?
...promising it's french speaking neighboors safety from China, she annex Luxembourg, Switzerland, Belgium and even western parts of Germany, Italy and Austria, while claiming Kaliningrad as a french territory.
How annexing these territories is going to make them safer, when distance between Luxembourg and Ural mountains (You didn't described borders of "People's Republic of Siberia", but generally Siberia starts east of Ural mountains) is ca. 3400 kilometres?
And what happend to all the countries that used to be located between "western parts of Germany" and Kaliningrad?
heavy protests sparks in NATO but they finally accept in exchange of a full autonomy of the non-french speaking territories.
Which countries are that NATO, in this configuration? And when France and NATO became at odds? Apparently sufficiently to have "accept the terms"?
France agrees for the terms but announce it would still have it's army on annexed territories and that inhabitants in the territories would have to learn french anyway.