Though little known to the outside world, Tawang is the biggest tinderbox in relations between the world’s two most populous nations. It is the focus of China’s most delicate land-border dispute, a conflict rooted in Chinese claims of sovereignty over all of historical Tibet.
In recent months, both countries have stepped up efforts to secure their rights over this rugged patch of land. China tried to block a $2.9 billion loan to India from the Asian Development Bank on the grounds that part of the loan was destined for water projects in Arunachal Pradesh, the state that includes Tawang. It was the first time China had sought to influence the territorial dispute through a multilateral institution. Then the governor of Arunachal Pradesh announced that the Indian military was deploying extra troops and fighter jets in the area.
This is an ongoing issue and nothing coming out of the blue, of course.
India needs to defend this area. Pakistan is no longer the main threat to India and India's defense posture must change to reflect this.
India's offensive options include supporting insurgents in Tibet and cutting off Chinese access to oil and raw material passing through the Indian Ocean. The problem is that these take time to have an effect and in the short run the Chinese might overrun Arunachal Pradesh.
In the longer run, it would be useful to India to have Vietnam and Taiwan as allies in case India needs to hit China's naval facilities on Hainan Island.