NEW DELHI — The disputed border region between India and China attracts troops from both countries, but two weeks ago the Chinese sent an unusual number of military patrols into the mountains of Ladakh, a remote high-altitude desert at the northern tip of India.

Two Chinese patrols came on foot, two more arrived in military vehicles and a Chinese helicopter flew overhead. With all the activity, the Indian authorities failed to notice until the next morning that about 30 Chinese soldiers had pitched three tents in an area both countries claim.

Indian military officials protested. The Chinese stayed put. India protested again. The Chinese, who had with them a few high-altitude guard dogs, responded by erecting two more tents and raising a sign saying, in English, “You are in Chinese side.”

As the dispute enters its third week, alarm in the Indian capital is growing. At a Thursday news briefing, Syed Akbaruddin, the spokesman for India’s Ministry of External Affairs, said, “There is no doubt that in the entire country this is a matter of concern.”