China’s move to build a $137 billion hydropower project in Tibet – which will be the world’s largest – has triggered environmental and security concerns in India, at a time when frosty ties between the neighbors appear to be thawing.

The proposed dam in the lower reaches of the Yarlung Tsangpo river, known as Brahmaputra in India, is expected to generate 300 billion kilowatt-hours of electricity annually, about three times the power of China’s Three Gorges Dam, currently the world’s biggest.

What’s the background?

The project was first announced in 2020. In December, China’s official Xinhua news agency said Beijing had given the green light to build the dam, despite concerns about how it may affect millions living in Tibet, India and low-lying Bangladesh.

When state-owned contractor Power Construction Corp. of China first unveiled the project, the company said it was critical to meeting Beijing’s carbon-emission reduction goals and promoting national security. India responded by warning that any diversion of water for the site would be an “encroachment of the entitled rights” of affected nations. India depends on the river for its own hydropower, agriculture and even drinking water.

The 2,900 kilometer river originates in the Tibetan plateau and enters India through the northeastern state of Arunachal Pradesh — a region China claims as part of Tibet — before eventually flowing into Bangladesh. Click here to read more details.