NATHU-LA, India (Reuters) -- As the rain sweeps across the high Himalayan pass, a Chinese soldier arrives at the three strands of barbed wire which separate his country"s territory from that of long-time rival India.

(来源：www.EnglishCN.com)

But this soldier is no longer brandishing a gun, on this once most sensitive of borders between the world"s two most populous countries. Instead he takes some video for his family back home and pauses to shake hands across the rusty fence.

Just a few yards away bulldozers on both sides of the frontline are building not fortifications but a road, to connect India and China and reopen a historic trade route.

New Delhi and Beijing plan to reopen the Nathu-la pass in June after more than 40 years, a potent symbol of rapprochement between Asian giants who fought a Himalayan war in 1962.

For an initial five-year period the pass, at an altitude of 4,310 meters (14,200 feet), will handle limited border trade between the tiny northeast Indian state of Sikkim and southern Tibet. It will be a modest start, but it promises much more.

"We are very much looking forward to the opening of the pass," said B.B. Gooroong, adviser to Sikkim"s chief minister. "It is symbolic ... but we have to break the ice."

The Sikkim government"s enthusiasm is not entirely matched in New Delhi, where the establishment still remembers being caught off guard by China"s sudden advance across the Himalayas in 1962.

Much of the 3,500-km (2,200-mile) common border remains disputed, and Indian officials say they are not yet ready to throw open the doors.

Nevertheless a gradual process is under way which could eventually lead to a significant trade route opening up from the Indian port of Kolkata to the Tibetan capital, Lhasa.

"They will go slowly, and there is still some distance before we get full-fledged transit trade," said foreign policy analyst C. Raja Mohan. "But there is potential."

A study commissioned by the Sikkim government suggested trade across Nathu-la could reach $2.8 billion a year by 2015.

Today that figure appears a little fanciful. It is hard to imagine anything larger than a minibus negotiating the narrow road that snakes for 56 km (35 miles) through the steep forested hills from Sikkim"s capital, Gangtok.

A few corrugated iron warehouses have been built to handle customs and immigration formalities, and a small trade mart erected to exchange goods at Sherathang, a chilly hamlet eight km (five miles) below the pass.

Nor has the Sikkim government yet won"s Delhi"s approval for its plan to build a new, two-lane 22-billion-rupee ($500-million) highway from Nathu-la to western India, bypassing Gangtok"s already congested streets.

But pressure is building from China, as it tries to bring economic prosperity and extend political control over its vast, remote and sometimes neglected west. Lhasa lies just 520 km (320 miles) by road from Nathu-la; Kolkata is a stone"s throw away compared to Beijing.

The passes between Sikkim and Tibet were once part of the Silk Road, a network of trails which connected ancient China with India, Western Asia and Europe.

Revived during British rule in India, trade across Nathu-la took off after independence in 1947 and China"s invasion of Tibet in 1950. A decade later, more than 1,000 mules and horses and 700 people took the narrow trail every day.

India imported raw wool, animal hide, and yak tails for use in shrines. It sent clothes, petrol, tobacco, soap, Rolex watches and even disassembled cars, including one for the Dalai Lama, the other way. Payment came in sacks of Chinese silver dollars.

Trade came to an abrupt halt in 1962. Five years later skirmishes at Nathu-la left scores dead on both sides.

As India and China rebuilt relations, two minor trade points were opened at the western end of the border in the 1990s, but agreement to open the more significant Nathu-la pass came during then Prime Minister Atal Behari Vajpayee"s trip to China in 2003.

At the same time China indicated it was ready to drop its claim to Sikkim, a former Buddhist kingdom which had merged with India in 1975.

"That was a very major landmark agreement from the political perspective," said one Indian official. "Now it is the economic side which will come into play."

Sikkim has few industries, but officials hope the local Dansberg and Yeti beers, produced at a factory in the south of the state, will prove popular across the border.

Even more exciting could be the prospect of tourist traffic one day crossing Nathu-la. Officials hope that Sikkim could eventually be the center of an international Buddhist pilgrimage circuit, from Tibet to Thailand and India to Nepal.

But even in Sikkim, there are concerns. Representatives of the mainly Buddhist Bhutia and Lepcha minorities are worried that unregulated development will bring in tens of thousands of outsiders and swamp their fragile cultures.

Truck traffic could bring alcoholism, prostitution and AIDS. Roads mean pollution, landslides and ecological damage, they say.

"Negative effects are bound to come," admits state industry and commerce minister Ram Bahadur Subba. "But development work has to be carried out."