“Some countries outside the region have used the Mekong’s water resources repeatedly for political purposes to spread rumours and exaggerate China’s threats, in a bid to sow discord and undermine cooperation between countries in the region,” he said, without naming the United States and its allies.

China promises Mekong neighbours access to Chinese Covid-19 vaccine

Around 60 million people rely on the waterway, but last year saw devastating droughts that had a devastating impact on farmers and fishermen downriver.

Luo was speaking as China launched a website to share year-round hydrological data about the upstream Mekong – known as the Lancang in China – and said the Mekong should be “a stage for common development, not a battlefield for geopolitics”.

The countries downstream have been asking China to provide data for years, and it has now started sharing information from two hydrological stations on the Lancang.

Beijing’s lack of transparency and series of dams built along the river in Yunnan province since the 1990s have long been a source of tension in the other countries that share the river, especially Thailand and Vietnam.

Although the intergovernmental Mekong River Commission rejected the allegations amid concerns about alienating China, the most important trading partner for Southeast Asian countries, the spat quickly escalated into a war of words between Beijing and Washington and its regional allies.

In an apparent bid to curb Beijing’s expanding influence in the region, Washington launched a new Mekong-US partnership in September, pledging investment of over US$150 million and greater support to ensure water and environmental security.

Are Chinese dams on the Mekong the next US-China battleground?

Zhang Mingliang, a Southeast Asian affairs specialist at Jinan University in Guangzhou, said Luo‘s remarks underlined Beijing’s growing wariness about the controversies being politicised.

“It is not surprising that China and the US have intensified their competition in the region and turned a cross-border water management issue into a geopolitical battle. China is clearly aware of its vulnerabilities over the construction of those big dams, which has constantly put China at odds with its downstream neighbours, environmentalists and international media and fuelled anti-China sentiments,” he said.

Zhang said the renewed tensions over Mekong also underlined the challenges China faced in managing its already strained relations with Vietnam, which is one of the countries worst hit by droughts and is also engaged in a prolonged territorial dispute with Beijing over the South China Sea.

“While Beijing can boast of its ties with other Mekong countries, Vietnam is an exception and its strategic mistrust and hostility poses the biggest headaches for China among Southeast Asian countries,” Zhang said.

While steps such as water data sharing were commendable, Zhang cautioned, “it is quite unrealistic to expect regional countries to edge closer to China considering the glaring trust deficit and misperceptions.”

Xu Liping, a specialist in Southeast Asia at the Chinese Academy of Social Sciences, also said that it would be hard for Beijing to stop other countries from seeking external support.

For instance, Vietnam may want to benefit from tensions over the Mekong to gain an advantage in the South China Sea dispute with the help of the US, Japan and other external powers.

“The move to share water data is a step in the right direction, which hopefully will help ease concerns among the downstream countries. But it’s going to be a long and difficult journey to win support from our neighbours in the US-China rivalry,” he said.