By Chris Morris
BBC News, Delhi
Indian PM Manmohan Singh is visiting the north-eastern state of Arunachal Pradesh over the next two days.
Indian troops have a long-standing border dispute with China
It is the first prime ministerial visit to the mountainous state in more than 10 years.
It is a particularly sensitive trip because neighbouring China, which borders the state, refuses to recognise India's sovereignty there.
Mr Singh was in Beijing recently as a guest of the Chinese leaders. Ties between the countries have warmed.
But the timing of Mr Singh's visit to the remote Indian state probably isn't a coincidence.
Indian officials have been concerned by recent Chinese statements about the border dispute, which has festered for more than four decades since the two countries fought a brief war in 1962.
Now Mr Singh is signalling the Indian intention to speed up the development of Arunachal Pradesh.
He will inaugurate a big hydro-electric scheme, as well as several road and rail projects.
Economic relations between India and China are booming, but other issues are holding back the strengthening of relations between the two rising powers of Asia.
Negotiations have been proceeding quietly for some years now on how to resolve disagreements all along their shared border.
But there aren't that many signs of real progress.