"That is excately what happens in the book"
In "Red Storm Rising," the Soviets arrange a terrorist incident in the USSR to make it look like West Germany is trying to provoke a NATO-USSR conflict in order to reunite with East Germany. They then attack West Germany and attempt to conquer it, gambling that the West (or at least enough of the West's public opinion to make a difference) would fall for it. NATO stands by while a NATO member is conquered and it collapses from sheer irrelevance and is thus not be a problem for their planned Middle Eastern adventure.
I don't think NATO weakness was an issue in the book, though of course, the Sovs would probably think of a worst-case scenario in which NATO stayed together and worry about that.
"That would be a good POD for a War between India and the Soviet Union"
But WI India and the USSR decided to cooperate? USSR gets Pashtun territories in west Pakistan (incl. the port of Karachi) added to Afghanistan or a new "Pashtunistan" state, while India gets the rest of Pakistan. India and the USSR were rather friendly during the Cold War due to India's leftish gov't and dislike of US-backed Pakistan.
The Soviets get the port on the Indian Ocean they've wanted since Peter the Great, which in the modern age will enable them to threaten the oil flow from the Persian Gulf, while India gets rid of a potential military headache. Plus, if the Sovs can blockade the oil route, that means no $$ for the oil states which means they'll eventually collapse (all they HAVE is oil).
Brezhnev wanted the petroleum "treasure house" of the Middle East in the East Bloc if he could get it (also the "mineral treasure house" of southern Africa); a Soviet-Indian move on Pakistan could be the first step.
Heck, that's a WWIII scenario right there. The US won't allow something THAT blatant to go by, and so air-naval attacks from Diego Garcia are launched on Indian and Soviet targets.