Almost anything the Dalai Lama does can trigger protests from Beijing. But his November 2009 visit to the disputed territory of Tawang, in the remote north-east Indian state of Arunachal Pradesh, was felt with particular resonance in China's capital. Relations between India and China have been bad-tempered for months, with nationalists on both sides urging their respective governments to act tough.
The Dalai Lama's presence in Tawang - which China sees as southern Tibet, and which was the birthplace of his eccentric but talented predecessor, the sixth Dalai Lama - reminds Beijing that this was once Tibetan territory. The current Dalai Lama first came through these parts in 1959, as a young refugee fleeing Chinese rule. He never returned to Lhasa. India's open-hearted hospitality to exiled Tibetans has annoyed Beijing ever since.
Arunachal Pradesh, nearly 33,000 square miles of lightly populated mountain and valley, is claimed by both India and China. Its people, largely Buddhist and ethnically Monpa, speak a language similar to Tibetan and have suffered long years of neglect by both states: a condition they no doubt prefer to being fought over. During the Indo-Chinese border war of 1962, Chinese troops occupied Tawang for more than a month. Now, China is reasserting its claim. India, in turn, is claiming more than 14,700 square miles of Chinese-controlled Aksai Chin, near the Kashmir border. Talks between the two countries have been held repeatedly over the past four years without resolution.
Today, the line of actual control is heavily patrolled by both nations: on the Indian side by troops housed in ramshackle, temporary huts, and on the Chinese by soldiers in concrete barracks marching along well-paved roads. The contrast has not escaped the notice of local people and is taken as a signal of intent.
The Dalai Lama's presence in Arunachal Pradesh and the warm welcome he received from his devout Monpa following are symbolic of the antagonism. But Beijing also issued a strong protest when the Indian prime minister, Manmohan Singh, visited Arunachal Pradesh last October during an election campaign.
Historically, China is Pakistan's ally and many in India believe that China maintains pressure along the 2,500-mile border that the two countries share to keep Indian forces tied down. There have been alarming reports in the Indian press of repeated incursions across the line of control by Chinese troops. The Indian government plays these incidents down, pointing out that the boundary is not only disputed but also ill-defined, and that these incursions need not be taken as provocation.
Behind the immediate stresses, there is jockeying for regional and international influence by two large, utterly developing economies, built on radically different political philosophies and lying in a region with both live and frozen conflicts. After 1962, relations were hostile for decades: China and Pakistan became allies, and India turned for support to China's enemy, the USSR.
The end of the cold war brought new conflicts based on ethnicity and religion, in a region with four nuclear powers. Recently, India has been alarmed by China's increasing presence in Sri Lanka and Nepal, historically Indian spheres of influence. Now, there is another factor to complicate relations - the impact of climate change on states divided by political boundaries but united in their dependence on the rapidly melting Himalayan glaciers for water, essential both for security and life itself.
Just a few miles across the line that divides Arunachal Pradesh from Tibet, the powerful torrent of what becomes the Brahmaputra River enters one of the most dramatic passages of its 2,000-mile journey to the Bay of Bengal. Rising on the slopes of the holy mountain of Kailash in western Tibet, it flows east, along the northern flank of the Himalayas, then enters one of the deepest gorges in the world, executing a hairpin bend before roaring south into Arunachal Pradesh.
To the engineers dominating the upper echelons of Chinese politics, who have the twin concerns of meeting China's ever-growing demand for energy and its need for water, the great bend of the Brahmaputra seems to offer an irresistible temptation.
Dammed if they do
Damming the great bend of the Brahmaputra is an idea with a long pedigree. It was first suggested as one of a series of global "megaprojects" by the Japanese in the 1970s. More recently, the Chinese government has made occasional reference to the plan. Though it remains a drawing-board idea, India suspects it is moving up the Chinese list of priorities.
Anxieties about China's intentions were inflamed in 2005 by the publication of the provocatively titled Tibet's Water Will Save China. Though it was not an official statement of policy, it was written by a former officer of the Chinese People's Liberation Army, Li Ling, and its wide circulation gave it sufficient stature in Indian eyes to merit careful scrutiny. Ling's enthusiasm for diverting Tibet's rivers, including the Brahmaputra, to northern China to alleviate the acute water crisis there fitted enough of the facts to set alarm bells ringing.
In many ways, it is an implausible project, but China's engineering record and its demonstrated love of ambitious dam projects are troubling to its neighbours, so much so, that many in India's security establishment have said that if China were to dam the Brahmaputra, it would be tantamount to a declaration of war. Doubts about the feasibility of the project, including those expressed by the more sober Indian civil engineers, have not dampened wider fears. For India, concern about China's ambitions for the Himalayan region rivals - and is linked to - its long-standing enmity with Pakistan. In the heated atmosphere of mutual suspicion, water has taken its place as a critical national security concern.
At a meeting between the Indian and Chinese foreign ministers in Bangalore in October, India sought, and reportedly received, reassurances over the Brahmaputra. China, Indian officials were told, is a responsible country that would not harm the interests of its neighbours. But reports that remote sensing has detected the beginnings of construction on the river at Zangmu, Tibet, continue to circulate.
Both India and China suffer long-term anxieties over water, now rendered more acute by the rapid melting of the glaciers of the Himalayas (from which all of the great rivers of Asia derive to some degree). In a region fraught with mutual suspicion and reciprocal bad faith, there are no source-to-sink, trans-boundary water management agreements in place and, currently, little prospect of any being negotiated to manage the sharing of what threatens to be a rapidly diminishing supply.
The dispute works both ways. While India protests about Chinese infrastructure investments in Pakistan-controlled Kashmir, which include roads and a £7.8bn dam, India has its own plans to dam the Brahmaputra in Arunachal Pradesh, which China opposes. India has drawn up plans for 42 dams in Arunachal Pradesh, which have the potential to produce nearly 28,000 megawatts of hydropower, equivalent to the entire hydro capacity built by India in the past 60 years.
The dispute over the dams went international in June when China attempted to block an Asian Development Bank loan that included £37m for projects in Arunachal Pradesh. The bank should not invest, China said, as the state was disputed territory. India responded by saying that it would finance the projects itself and stepped up its military presence in the region, deploying another 60,000 troops to the neighbouring state of Assam in addition to the 40,000 already stationed there. The shadow war games rapidly spread across the Himalayas, as China initiated military exercises. In September, India responded by stepping up the state of alert on the line of control in Kashmir.
The status of India's legal claim to Arunachal Pradesh is complicated and rests on the unresolved argument about the historic status of Tibet. It centres initially on an exchange of notes during the negotiation of the Simla Accord in 1914, under Henry McMahon, the then foreign secretary of British India. China, Tibet and Britain negotiated the accord, which resulted in the contentious McMahon Line that, for the British at least, defined the border between India and Tibet. The Tibetans conceded the territory that became Arunachal Pradesh to British India in return for a British promise, never honoured, to recognise Tibetan autonomy.
Chinese water torture
China rejected the Simla Accord and insists that Tibet did not have the status to sign any international agreement. If India were to rest its case on the accord, it would imply that Delhi recognised Tibet's authority to negotiate and conclude international agreements: a step that Beijing would take as severe provocation. The British, at the time, insisted on a distinction between China's acknowledged "suzerainty" over Tibet and full sovereignty, but the picture was further complicated last year when the Foreign Office abandoned the distinction, for current policy at least, as "anachronistic".
After Simla, neither side paid much attention to the disputed territory, and the Tawang monastery continued to pay taxes to Tibet until the 1950s. Shifting regional geopolitics have made this, and other Himalayan regions, the focus of potentially dangerous rivalries.
For the Tibetans in exile, these developments carry their own threat. Rising tension between their Indian hosts and Beijing is not good news. India has been a generous host to some 150,000 Tibetans who now live there, to the Dalai Lama and his government in exile, and to refugees who continue to arrive.
Yet there are voices in India which argue that, in the face of China's growing assertiveness, the cost to India of this spiritual and material solidarity is getting higher. It is not hard to find Indian analysts who believe that both India and China need a comprehensive agreement on the main points of contention between them - the border and the disputed territories, the fair management of declining water supplies, and the scientific and technical co-operation that such agreements would demand.
The question that many ask, but nobody has yet answered, is whether the price of a comprehensive agreement will be the special status and security that India's Tibetan exiles have enjoyed for more than half a century. Such a bargain would certainly please Beijing. For India, it is still a long way from official policy, but some argue it would be a price worth paying.
Isabel Hilton is editor of chinadialogue.net