Since the joint investigation into the Cheonan incident coincided with the second China-US Strategic and Economic Dialogue, it became a bargaining chip for Washington to check Beijing. By doing so, Washington could "kill two birds with one stone". On one hand, it could urge China to put political and economic pressure on the DPRK, weaken Beijing-Pyongyang ties and get a chance to play a greater role in the peninsula's nuclear issue. On the other, it could consolidate its alliance with Seoul and Tokyo, and thwart the process of East Asian integration, especially the formation of a China-Japan-ROK free trade area. An added bonus would be the chance to present the Obama administration's so-called tough image to voters in the run-up to the 2010 mid-term election.

In order to complete the DPRK's isolation from the rest of the world, the US is trying to present it as a "troublemaker" and drive a wedge between Beijing and Pyongyang, and finally force the DPRK into total submission.

The blows dealt by the global economic crisis have made Japan and the ROK more economically dependent on China, which has been maintaining its fast growth. China, Japan and the ROK have already held a few high-level meetings aimed at promoting East Asian integration. This scenario doesn't suit America's economic, political or strategic purpose, but it cannot prevent it openly. So it is using the Cheonan incident to woo the ROK and Japan, and distance them from China - which would thwart East Asian integration. The resignation of Yukio Hatoyama as prime minister of Japan a couple of weeks after the Cheonan investigation results were announced was one outcome of the US maneuvers.

Obama faces a tough mid-term election because of a drop in his administration's approval rating, rightwing forces' tirade against his policy toward China, and the Republicans' opposition to his health reform. To regain its popularity rating and diplomatic initiative, the White House needs to show its toughness. And how better to do it than to stand firm behind the ROK over the Cheonan issue, hint at sending the nuclear-powered aircraft carrier, George Washington, to the Yellow Sea for military drills, and insist (through the US defense secretary) on selling arms to Taiwan.

The instability on the Korean Peninsula is detrimental both to China and the ROK but is advantageous to he US. By imposing new sanctions against the DPRK and selling arms to Taiwan, the US could ease the domestic economic crisis and unemployment pressures, and expand consumption and boost its military industry.

Though the finding of the international investigation team in the Cheonan incident is suspicious, Washington and Seoul are pressuring China to make the DPRK accept it. Public focus in the ROK has turned to China, with the US again playing the morality card. If the United Nations Security Council endorses the finding, coalition forces, led by the US, could launch attacks against the DPRK and try to draw China into the game.

China has to act like a responsible power for the world, not only for the US. The ultimate victims of the Korean Peninsula crisis are the people living there. Actually, Washington is full aware that even if it could temporally shift Americans' attention from their domestic problems by starting wars and stirring up conflicts in Northeast Asia, they won't be in the region's or its own interest in the long run.

The author is a professor at the School of International Studies, Renmin University of China.