Abstract: The Tumen River Area Development Project is a plan for a transport mega-complex at the mouth of the Tumen River on the Sea of Japan. Because the three major stake-holders are the People’s Republic of China, Russia and the Democratic People’s Republic of Korea the project raises complex jurisdictional and economic problems. We review the context in which the project was established and then outline the evolution of the various plans for development of the region. Next the conditions for judging the efficacy of the project in both the short run and the long run are presented in the context of regional trade. The Tumen Project may well play a significant role in stimulating the local regional economy, including Mongolia, and help raise the rate of economic growth in that part of Northeast Asia which has so-far lagged behind the rest. There is, however, a danger that if the project is implemented on too large a scale it may simply duplicate facilities in the region with no consequent aggregate benefit. The level of cooperation required among the stakeholders is high for the project to succeed and overcoming this impediment is still the project’s greatest challenge.