Assertion: A boundary dispute had surfaced between India and China. India claimed that the boundary was a matter settled in colonial times.
Reason: The China war dented India’s image at home and abroad. India had to approach the Americans and the British for military assistance to tide over the crisis.

Both the Assertion and the Reason are correct but the Reason is not the correct explanation of the Assertion.

A boundary dispute had surfaced between India and China. India claimed that the boundary was a matter settled in colonial time, but China said that any colonial decision did not apply. The main dispute was about the western and the eastern end of the long border. China claimed two areas within the Indian territory: The aksai-chin area in the Ladakh region of Jammu and Kashmir and much of the state of Arunachal Pradesh in what was then called NEFA (North Eastern Frontier Agency). Between 1957 and 1959, the Chinese occupied the Aksai-chin area and built a strategic road there. Despite a very long correspondence and discussion among top leaders, these differences could not be resolved. Several small border skirmishes between the armies of the two countries took place.