From PTI:
Amidst warming of ties, China has taken exception to Prime Minister Manmohan Singh’s visit to Arunachal Pradesh and his assertion that the state belongs to India, evoking a strong reaction from New Delhi.
Almost a week after Singh visited Arunachal Pradesh and said the state was “our land of rising sun”, Chinese Foreign Ministry officials have conveyed to officials in the Indian Mission in Beijing that they were unhappy with the visit and his comments there.
Beijing feels that it was not appropriate for the Prime Minister to visit a state, major parts of which it claims are its territory.