Two countries and a shared river: Mistrust is not inevitable

India's most important rivers rise in a region it cannot see into, controlled by China, which treats the data about them as an asset to switch on and off. The Brahmaputra rises as the Yarlung Tsangpo in Tibet, entering Arunachal as the Siang; the Sutlej and Indus rise there too. What India knows of them at their source, it knows because Beijing chooses to tell it. India and China have no water treaty — only two flood-season memorandums, on the Brahmaputra (2002) and the Sutlej (2005), for which India pays roughly a crore a year, plus a consultative mechanism that meets when relations allow. The edifice is deliberately flimsy: China shares data, but on its own terms and its own reading of what sovereignty permits. Both India and China, tellingly, stand outside the 1997 UN Watercourses Convention, which would oblige upstream states to give prior notice and not harm those below. China voted against it; India abstained. A non-binding memorandum can be suspended without breach. In 2017, during the standoff at Doklam, China stopped sharing Brahmaputra data, blaming damaged collection sites, even as that summer's floods killed scores in Assam. It resumed once relations thawed, then dried up after the 2020 Galwan clash; the memorandum lapsed in June 2025. Flood prediction data is not a neutral public good but a lever — released when ties are warm, withdrawn when they are not. Beijing tells a different story. It blames the stoppages on technical faults, calls the dam 'fully within China's sovereignty' and promises it will 'prevent and mitigate disasters'. Some of that may be true. But I recall a Chinese scholar's remark on a state-controlled visit to Tibet in a delegation I joined: He pointed at a river and made a snide comment, 'That is a river that flows into India, and we can stop it any time we want.' Every reassurance shares one flaw: Those meant to be reassured cannot verify it, because the region is sealed. If the flood is the symptom, the dam is the escalation. In July 2025, China broke ground on the Medog project at the Great Bend of the Yarlung Tsangpo just before the river turns towards Arunachal. At 60 GW, it will be the world's largest hydropower project, in one of the planet's most seismically violent zones — the same tectonic seam that produces the outburst floods now hitting the border. Arunachal's chief minister has called it an 'existential threat' to Siang valley; Bangladesh, at the river's end, sought details in early 2026 and got none. The plateau is so opaque because of how China governs Tibet — as a colonised space, held through near-total domination. India, which hosts the Dalai Lama and the largest Tibetan exile community, is viewed with particular suspicion. Yet this is no morality tale of Chinese secrecy against Indian virtue. India has been complicit in its own exposure: Successive governments have settled for the paid-data memorandum and not pushed for the binding, basin-wide architecture that would make information a right, not a favour. Nor is India only a victim. It is an upstream withholder too — sharing thinly with Bangladesh and, this year, suspending the Indus Waters Treaty with Pakistan after the Pahalgam terror attack. The logic it faces on the Brahmaputra is the logic it practises on the Indus. None of this is inevitable. On the Senegal River, four of the world's poorest African countries jointly own their dams as 'common and indivisible property', sustaining it even through a war between two members. If states this impoverished and mistrustful can pool sovereignty over a river, China's refusal is a choice, not a constraint — as its absence from the Mekong Commission its neighbours built confirms. India's water future is tied to a plateau it can neither see into nor shape, held by a mistrustful neighbour across a hot border. The question is not whether India can force China to open up, which it cannot, but whether it will build the institutions that make hazard information a shared necessity, not a bargaining chip. The two must also decide whether a shared river is a common lifeline or a weapon held in reserve. The writer is professor of International Relations, University of Westminster, London