It was an unprecedented move when China announced it would speed up the discharge of water from a dam in south-western Yunnan province to ease the concerns of drought-stricken countries downstream of the Mekong River.
Two days after the Chinese government said it would "overcome its own difficulties", the Mekong River Commission (MRC) - which comprises Thailand, Vietnam, Cambodia and Laos - thanked Beijing for its "goodwill".
"It would ease drought and help irrigation in some parts of the region," Dr Pham Tuan Phan, the MRC Secretariat's chief executive officer, said in a statement.
Beijing's gesture last week was politically significant. Given that China is due to host Vietnam, Cambodia, Thailand, Laos and Myanmar in the inaugural Lancang-Mekong Cooperation (LMC) leaders' meeting in Hainan tomorrow, the announcement sweetened the ground for the China-led regional initiative, which aims to tackle cross-border economic cooperation and poverty alleviation, as well as the management of water resources.
Like the China-led Asian Infrastructure Investment Bank launched this year, the LMC framework offers another opportunity for Beijing to extend its regional influence.
"Mekong is what China considers its backyard, where it could put a stamp on, too," says Mr Apichai Sunchindah, an independent Thailand-based development specialist.
Lancang is the name the Chinese use for the upper reaches of the Mekong, which originates in the Qinghai-Tibet Plateau. The river travels more than 4,000km through Myanmar, Laos, Thailand, Vietnam and Cambodia, before draining into the South China Sea.
MRC member countries are bound by an agreement to inform or consult one another if they want to divert water from the Mekong. China - which contributes 13.5 per cent of the flow of the Mekong River - is not a member of the MRC. Like Myanmar, it is only a "dialogue partner".
Chinese dams upriver were constructed without prior consultation with MRC countries. In 2002, Beijing agreed to share data on water levels during the wet season from two stations located on the Lancang River, to help the MRC's flood forecasting system. But its other operations remain a mystery to countries downstream.
Environmental advocacy group International Rivers notes that "severe droughts in the lower Mekong basin in 1992 and 2010, which were partially attributed to below-average rainfall, also coincided with the filling of new power stations' reservoirs on the Lancang".
This is not to say that China is totally responsible for the dry weather woes of its neighbours downstream. Laos, an impoverished, landlocked country which sees hydropower as a ticket to foreign exchange, has also been criticised for disturbing the Mekong ecology through its own dams. A major beneficiary of Laotian dams is Thailand, which imports electricity to reduce its reliance on fossil fuel.
Meanwhile, Thailand is making its own plans to dam the Mekong's tributaries in the north-eastern corner of the kingdom, much to the consternation of Vietnam, where rising salinity of water is destroying its crops.
With so many dams upstream, farmers or fishermen on the river live at the mercy of those controlling the taps. During the dry season, it is common for locals to set up small shops serving tourists on islands created by the receding waters of the Mekong. Many of these pop-up shops were destroyed during the past few dry seasons by the sudden rise in water levels, says International Rivers' Thailand coordinator Pianporn Deetes. In the light of this, would the Hainan meeting "build a mechanism for accountability for leaders", she asked.
Given the feeble mechanisms governing water use on the Mekong now, many are watching the Hainan meeting closely, to see if the Chinese leadership would help forge genuine water-sharing commitments among all riparian countries.