Wipe out an area the size of India, with just 1 megaton in fission bombs, and insufficient numbers of delivery systems that can reach so far?
How many medium/long range missiles will you need, to take out even one large city with 20kt fission bombs? More than a handful.
Whereas ONE single Chinese nuke is 3-5 megatons a piece (one nuke has more power than India's entire arsenal), so one is more than enough to take out a large city. And we have one of the largest numbers of short-medium range missiles in the world.
But of course, the odds are that India will be handled by Pakistan (who have the fastest growing nuclear arsenal in the world) in such a scenario.
And your leaders don't have the stomach to expand such a localized nuclear conflict.