The most likely route will be either through Bangladesh (which will also have its own climate change problems) or the north east. India already took Sikkim via the route of ethnic replacement and tried and failed to take Myanmar with its mass of walking useless mouths.That’s pretty bad... I mean... it’s not like any of India’s neighbours are in a position or are inclined to take these people in... perhaps instead of spending all this money on weapons procurement they should focus on building and running desalination plants for the short term while solving the problem long term... tho I doubt the Indian gov is even interested in solving the problem...
If masses of refugees starts moving... they could create a literal human wave tactic just so they can get water to live... that’s really sad...
I've always maintained that in the event of war, there should be a buffer zone at the base of the indian side of the Himalayas, enforced with neutron bombs and drones. Maybe these same drones can herd the remaining indians to the Thar desert and leave the rest of the foot of the Himalayas as an untouched nature preserve.