Just weeks after Laos announced its plans to begin constructing a third mainstream dam in the Lower Mekong River region, Prime Minister Hun Sen used a bilateral meeting with his Laotian counterpart to signal that the controversial Don Sahong dam will no longer receive opposition from Phnom Penh.

“After Cambodia inspected the situation, it does not have a problem with this development project,” Hun Sen wrote on his Facebook page, thanking Laos for its pledge to sell low-cost electricity to Cambodian provinces located near the dam.

Laos first announced its plans to build the controversial 260-megawatt dam in 2015. According to a 1995 Mekong River Commission agreement, Cambodia, Laos, Thailand and Vietnam must engage in joint discussions before big development projects are launched.

But critics say downstream countries have no real power to impact the plans, since Laos began constructing two controversial dams, the Xayaburi and Don Sahong, despite concerns from Cambodia and Vietnam.

Cambodia’s about-face shows the consultation process has failed to ensure concerns from downstream countries are addressed, said Maureen Harris, Southeast Asia program director for NGO International Rivers.

“Thousands of people in the Mekong Basin rely directly on the river system’s rich fisheries and agricultural productivity for basic food security. With two dams underway on the Mekong mainstream, the impacts of each new project, particularly on fisheries and sediment flows, will be cumulative,” Harris said in an email.

Laos submitted plans to the Mekong River Commission earlier this month to begin constructing the Pak Beng dam, launching another round of discussions in which Cambodia will participate. Laos has previously said it hopes to be the “battery” of the region, and has floated ideas for 11 mainstream dams.

Tek Vannara, executive director of the NGO Forum, said civil society remains concerned about the potential environmental impact of mainstream dams, and called on Laos to complete an environmental impact assessment for the Don Sahong.

“The experts of Laos have not revealed transparent scientific information relating to the impacts and solution mechanisms yet,” Vannara said. “We want government leaders to make a decision based on the technical conditions rather than on politics and economics.”

The World Wide Fund for Nature Cambodia has said that the Don Sahong is a risky project that could affect the food security of millions of people.