And to use DF11,15 ballistis missiles, or cruise missiles to just like to use cannons hit mosquitos - not worth it, acturally.
Long before the second artillery missile force put into use, long-range artillery rocket force could pretty much blanket-bomb most of Northern India, in which most of India's economical, political and millitary centres are.
Trust me, whole Northern India are well within China's long-range artillery rockets coverage. And we can produce those artillery shells cheaper than spaghetti.
Yeah, spaghetti! Meety sausages are only used for levels of your PM or generals' bedrooms, etc...
What if? Taiwan, the US, Russia, oil supply...?
What if what? None of them has a slight illusion of fighting China force for force as India does.
Within a matter of hours, with some help of precision "sausages" DF11,15 later on, the whole India will be paralized - the North part, the South, the West and the East.
Now save that "nuclear" sub kindergarden toy you just have, will ya? If it were somehow "indeed" nuclear-powered, and if it could "indeed" launch a missile from underwater, 700km range can not even shoot a duck, let alone that noise, which could wake up most of the cows of Inner Mongolia one step after it slips into the Indian Ocean...
War? Keep fantasizing in your cartoon video game!