For most of human history, envirinmental impacts such as pollution or overexploitation have been seen and treated as local problems. Nowadays, however, environmental issues connect local, national and international processes and therefore appropriate responses to environmental problems are needed in an interdependent world. Environmental cooperation is an important challenge for East Asia and has been recognised and addressed in the Mekong region by each of the six riparian countries nationally, as well as collectively through bilateral and multilateral agreements.