Plans and reality are two different categories.
Secondly, please recall that the PLA in the north-east is in precisely the same topographical situation as the Indian Army in Kashmir; it is poised on the edge of a plateau, faces a frontal area of deep ravines and forested slopes, and has in front an opponent within these ravines and forested slopes and also in very well-connected low-level flatlands at the edge.
Just as the Pakistan Army can mobilise its armour and SP artillery in the low-level flatlands fringing the slopes of the Valley of Kashmir, the Indian Army needs to retain some part of its armour in the north-east to receive a Chinese push down the Arunachal slopes. The IA no longer thinks in terms of braving disproportionate Chinese numerical superiority at the end of its own communications lines with Mountain Divisions tasked to stick it out against all odds, and risking being cut off by swift Chinese advances through the ravines, as has happened in living memory.
It is also true that doctrine on this matter is in a state of flux; even while this debate is going on, India has given the Army the mandate to raise more Mountain Divisions. That is obviously a matter of some long-term importance; either the PLA should be faced on the plains, in which case Mountain Divisions will play only a diversionary role; or the PLA should be fought every inch of the way within the ravine and forest country, in which case there is all the responsibility of determining the opponent's most probable line of advance, and an enormous strengthening of logistics chains, far beyond present capabilities, but a maximum number of Mountain Divisions should be raised; or the PLA should be fought on the Xijang Plateau itself, a possibility that should not be ruled out of doctrinal deliberations, given certain trends and features that are in evidence.
For this last alternative, the type of formation needed is obviously vastly different from the other two scenarios, and nobody will prepare for warfare on that foundation unless something radical happens in the geo-strategic space. Also this last will take the kind of careful preparation that the PLA itself undertook in 1962;for nearly a year in advance, the build-up of supplies had begun (in the north-east only), some of this build-up ironically through Calcutta Port, and shipped out through mule-trains to the Chinese strong points. The PLA did not display overwhelming superiority in materiel accidentally; it was planned months ahead. Similarly, any plan to fight on the Xijang Plateau cannot depend on accidental superiority.
Where these choices dovetail with the concept of Independent Battle Groups that are being thought of for the western front is not yet clear. Will the northern front, facing the PLA, also see the introduction of this type of all-arms formation? What will the objectives be, how large will the formations be, how should they be armed - all these issues are under discussion at all times, and nothing has emerged in definitive terms on these issues.
At the end of the day, where Mountain Divisions fit into the big picture is still a matter of constant review. These were designed for the
middle of the last nineteenth and twentieth centuries, where fighting on the NWFP determined their evolution and structure; these were specialist units with one purpose in life and one only. Their role in post-partition India has been migrated to the Kashmir peripheral area, and, more important, to the front in Arunachal.
They face two entirely different adversaries; one, a frugal, economical foe adept at reacting quickly and concentrating force quickly to forestall any attack, and equally practiced in mounting very aggressive attacks given the slightest opportunity, and focussed on defeating the Indian Army as its primary objective; the other, a lavishly-equipped organisation that has just undergone major transformation, has outstanding logistics, has its own industrial capacity for all types of war-fighting equipment, but is lothe to give battle because its entire concentration is on its own sea-coast, facing a breakaway province and an aggressive superpower.
Very clearly, there will be changes in the role and responsibilities of Mountain Division, and it may not be that all Mountain Divisions are identical. It may well be that, like Independent Battle Groups, these formations or their successors are organised around a central tactical and grand tactical objective, distinct for each Mountain Division, aggregated into strategic objectives at a higher level. It may be expected that the nomenclature will be retained but the cross-section of each formation is different, and they are each unique.
Above all, it needs to be borne in mind that the Pakistan Army is not the only thing in the mind of the Indian COAS as he shaves in the morning; he has other headaches as well. Secondly, whatever he may decide, after long and serious thought, in close consultation with other military leaders, the civilian decision-makers have their own time-frames and these do not always lead to successful outcomes. General Sunderji found this out to his cost, and each successive Chief has worried about initiating change and being unable to see it through, leaving his institution precariously poised between two stools.
@jbgt90