For much of its history, India has regarded the Himalayas as a form of protection, not a barrier to be overcome, said Rajeswari Rajagopalan, an expert in India-China relations at the Observer Research Foundation in New Delhi.

“The Indian side has been very slow to develop the border areas,” Ms. Rajagopalan said. “They believed if you improved the infrastructure it would only allow the Chinese to walk into your territory. This was very foolish and naïve.”

Three hundred miles of winding road lead from the town of Manali, through the verdant Kullu Valley, to Ladakh, an alpine desert that abuts the Tibetan plateau.

Tens of thousands of Indian Army troops are stationed among Ladakh’s barren peaks, and the region borders several potential trouble spots, including Aksai Chin, a region that India claims as part of its territory but that China administers. North of Ladakh is the Siachen Glacier, a river of barren ice that India and Pakistan have fought over intermittently since the 1980s. Both countries maintain outposts on the glacier, which sits at an altitude of 20,000 feet.

During the summer, thousands of trucks, laden with supplies to last the harsh mountain winters, rumble up the two roads that lead to Ladakh, from Manali and Srinagar, the summer capital of Indian-administered Kashmir.

The road from Ladakh to Srinagar is also closed in the winter, and because of its proximity to the Line of Control that splits Kashmir between India and Pakistan, Indian officials worry that the road can easily be cut, as it was in 1999, when the two countries clashed at Kargil.