China and the United States still have much in common and their economic interdependence still deepening.

Chinese people feel particularly bewildered over the United States' motives behind its recent military drills with its Asian allies in Northeast Asia and its unrestrained interventions in China's territorial disputes with some Southeast Asian nations in the South China Sea.

The ups-and-downs of Sino-US relations over the past three decades have largely been driven by national interests, in which the two countries have endlessly changed their diplomatic approach towards one another according to their changed interests during different periods.

Since the start of the new century, Sino-US relations have expanded beyond the bilateral basis and an increasing number of regional and international issues have been included in their dealings with each other. As a result, disagreements between the two big powers have increased both in the regional and global dimensions.

A typical example is Washington's policy in Southeast Asia. In their recent self-reflections on US policies towards the region, some US politicians and scholars argued Washington's absence in the region over the past 20-years has contributed to an imbalance of power in the region. The high-toned announcement by US President Barack Obama's administration that the US has "returned" to Southeast Asia testified the US' intention of regaining dominance over the region's affairs.

Washington's motives for deepening cooperation with the Association of Southeast Asian Nations (ASEAN) are beyond reproach if they are in the interest of the region's stability. But the case is different if its involvement is unbeneficial to the settlement of territorial disputes among the parties concerned in the region.

The US has never implicated itself in territorial disputes in the South China Sea and all US administrations have adopted a neutral stance on this issue until recent months. Even during Obama's visit to Manila in June last year, US Secretary of Defense, Robert Gates, said the US's policy in Southeast Asia was not to be involved in regional territorial disputes.