Even aside from building up forces to oppose China, India can't even move and support the forces they have if India needs to reinforce the northeast:
It has been a year since India and China ended the 73-day border crisis in Doklam. And for all the focus on the crisis itself and its implications for Sino-Indian relations, it is worth recalling that along their border, Doklam is arguably an exception where the Indian military may be perceived to have a slight advantage over the Chinese military because of its slightly better infrastructure there.
Relatively speaking, however, the infrastructure on the rest of the border is quite appalling. Indeed, unless India accelerates the pace of the physical border infrastructure build-up, New Delhi will face serious difficulties in any future confrontation with China.
The Indian vice chief of army staff, in his statement to the Indian parliament’s Standing Committee on Defense, voiced serious concerns on the lack of adequate allocation of funds for the Army for 2018-19. He pointed to the “large number of Chinese strategic roads and infrastructural development along the northern borders” and made a case for bigger resource allocation, given that the sanctioned budget for infrastructure development was running massively short.
When you consider that American logistics enables the movement of significant American military power globally (if you wonder why we spend so much, this is one reason), this Indian shortcoming is inexcusable.
Although it is true that building such infrastructure really would facilitate a Chinese invasion, which was the Indian motivation for keeping the infrastructure weak. So if India builds that infrastructure, India had best build up the forces to hold the territory.
Which is why India
Without both of these infrastructure and force developments, China gets there first with the most to dig in and dare India to counter-attack a nuclear-armed China.
UPDATE: India has a need to contain China and so does Russia, so the old friendship between India and Russia is worth sustaining:
President Vladimir Putin will discuss military cooperation with India when he visits the country this week, the Kremlin said on Monday, without specifying whether the possible sale of S-400 surface-to-air missiles was on the agenda.
India has had no problem in getting closer relations with America to cope with China. Why can't Russia see the same advantage?
