Aside from supporting efforts of the 10-member Asean, which the five Mekong states are part of, to be more integrated economically, Japan's engagement in resource-rich Mekong is also seen as countering China's growing political and economic clout there.
With China's recent rapid and large-scale reclamation work in the South China Sea in mind, Abe and the five Mekong nations' leaders, in a document unveiling their new strategy for cooperation, "noted concerns expressed over the recent development in the South China Sea.