The Indian defence establishment is cautious about the opening, with defence sources telling an Indian newspaper, the Hindustan Times, that they feared infiltration of Chinese spies into Sikkim.
Tibet is already among the most heavily militarised regions of China.
Indian strategists are preoccupied with what they see as the gradual "encirclement" of India and south Asia by China, which has improved ties with India's neighbours, including Burma, Bangladesh, Pakistan and Sri Lanka.
Jul 7, 2006
China and India reopen Silk Road
The Nathu-La Pass, at the border of the Indian state of Sikkim and near the border of Tibet, has been closed since 1962.