A brief analysis of geography and surface infrastructure in Sikkim and how it impacts the force deployment from Indian perspective.
(a) Geography - First things fist – let us look at the geography of Sikkim and the available infrastructure. The state extends in north-south direction with length being more than the breadth. It has border with Tibet on its north and east while on its west it shares boundary with Nepal. To its south lies the state of West Bengal.
The northern and eastern borders with Tibet are the areas of interest to us.
The Sikkim-Tibet border in east runs in north-south direction and in its entirety is a high ridge line with mountain ridges north of 4,000 meters in height and crossing 5,000 meters easily as one goes north. The valley floor in southern part of this border (on Tibet side) is less than 3,000 meters and goes up to 3,500 meters as one goes north. Except for certain areas in northern section of this border with passes which can allow for lateral movement of troops, the area will not permit any large scale east-west movement of troops. Except for the vegetation, the geography resembles the one obtained along LOC north of Northern Gullies in Ladakh. Interestingly, there are some valleys which go in east-west direction (up to ridge line) and if one observe Google Earth one can observe that Chinese have tracks and troop deployment in these valleys leading right up to border. There are similar such valley running in west-east direction on Indian side.
The link to the map below is zeroed on the Sikkim-Tibet boundary in east.
(b) Infrastructure - Now, consider the infrastructure available on Indian side. There is grand total of ONE major road which runs in south-north direction – the North Sikkim Highway (NSH). This road bifurcates at a key point (Cheungtong) and serves eastern and western shoulders of Northern Sikkim. It is this road which provides connectivity with most of the areas on Sikkim-Tibet border in east – from what I could make out on the map, extreme North and North East Sikkim are served by the western arm of the North Sikkim Highway as eastern arm cannot reach these areas because of a massive mountain ridge.
The eastern arm of NSH runs close to eastern Sikkim-Tibet border and at many places is under 15kms. The important town of Cheungtong is also under 20kms from the border. PLA could make a grab for the eastern arm of NSH and the town of Cheungtong - capture of these two objectives would cut off eastern part of northern Sikkim and isolate the Indian garrison in North and North Eastern Sikkim.
Similarly, the northern and north eastern parts of Sikkim are connected by one major road – the western arm of NSH. One important aspect to understand here is that the extreme north and north-east parts of Sikkim are extension of Tibetan Plateau – the famous Fingers Area is also here. Because of similar geography as Tibet, the area is relatively flat and gives opportunity for breakout – road S 204, the main communication axis which connects the Chinese positions in Chumbi Valley with Tibet mainland, runs under 10kms towards east from north-eastern Sikkim. There have been press reports which say that IA wanted to deploy an armored regiment in the area.
However, while these areas are relatively flat and even, the area leading to them and through which the single communication axis passes is not – the road passes runs along narrow river valley with steep mountain sides and which are prone to landslides.
You can look up the road network here:
(c) Troop Strength - So, what does all the above gyaan about geography tell you? That given the lack of suitable infrastructure, India will be required perforce to hold these areas like stand alone sectors – which means there have to be more ‘forces in being’. Even if the forces are not deployed right along the border, they will need to be maintained at relatively short distance (mostly within Sikkim or close to Sikkim) from where they can be quickly moved to their future deployment area. Lateral movement between sectors in mountains is never an easy option to begin with - lack of infrastructure on Indian side simply makes that impossible. So, not only will the ‘forces in being’ be required, even the reserves need to be maintained fairly up – and too, dedicated reserves for each sector.
The moment balloon goes up, the road communication will see love and affection from the PLA which is tenuous to begin with – which means IA will be required to move men and material upfront in whatever lead time it has. Mountain warfare eats up men and material and given the road infra situation in our case (and need to acclimatize), we need to over compensate. I hope that explains the ‘LARGE’ force deployment by India in this sector relative to the PLA.