On December 11, Cambodian Prime Minister Hun Manet met with his Vietnamese counterpart Pham Minh Chinh on an official visit to Vietnam’s capital Hanoi. During the two-day visit, the two sides engaged in discussions over such issues as defense, border affairs, trade, and education. They also signed cooperation agreements in the fields of science and trade.
During his talks with Manet, Chinh expressed his concern over Cambodia’s Funan Techo Canal project. He was worried that the project would negatively affect the environment and the water system of the Mekong River, especially the downstream water flow from Cambodia to Vietnam. In response, Hun Manet reassured him that the preliminary studies on the project indicated that the environmental impacts on Vietnam would be minimal.
In full: https://thediplomat.com/2024/01/why-is-vietnam-worried-about-cambodias-mekong-canal-project/