As the U.S. and South Korea expressed solidarity in blaming North Korea for its attack on the South Korean warship Cheonan and in imposing further sanctions on North Korea, global attention is now focused on China with regard to whether it will cooperate in inflicting punitive measures on its ally. Despite the worsening cleavages between China and North Korea since October 2006 when the latter tested its nuclear weapons, this study shows that their relations has remained robust in the economic context although it has experienced a political transition. This paper begins with the Sino-DPRK relations by exploring the status of the alliance in transition in the political and military context. Further, it considers the economic context between the two nations by reviewing Chinese aid to North Korea and North Korea's trade data, using the gflow of goodsh as a proxy for "low of money." Then, this paper applies North Korea's strategic interaction with the U.S. in the game theoretic methods in order to illustrate the Chinese impact on the efficiency of economic sanctions on North Korea. The study found that China's role remains consequential as the strategies of North Korea and the U.S. depend on China's position in their strategy interaction.