Applying some strategic ambiguity in the South China Sea would be useful to ensure the stability and prosperity in the Asia-Pacific

Even though President Xi Jinping and his US counterpart Barack Obama held summit talks on Tuesday and Wednesday following the 2014 APEC Economic Leaders' Meeting, the Sino-US relationship still has uncertainties.

At least until this week, the outlook for a new type of major-country relationship seems to have darkened 18 months after their summit in Sunnylands, California, and there are growing concerns that China and the United States might descend from competition to rivalry. The Asia-Pacific would doubtlessly be the main arena should that be the case.

The US is increasingly worried about China's long-term policy intentions as it seems to be taking a harder line on the territorial disputes in the South China Sea and East China Sea. As China has also refused the proposal by US Secretary of State John Kerry to "freeze" these disputes, the US also feels its elevated role as "arbiter" is being challenged.

In addition, at the 2014 Conference on Interaction and Confidence-Building Measures in Asia, held in Shanghai in May, Xi raised a new concept of Asian security advocating that "Asian people be responsible for Asian affairs". Although he expressed that the region would welcome positive contributions from other parties, the move was widely interpreted by US strategists as trying to "edge" the US out of Asia and build a regional order without Washington.

Further, 21 economies in the Asia-Pacific have signed up as founder members of the Asian Infrastructure Investment Bank, which was initiated by China. A Silk Road Fund of $40 billion has also been set up by Beijing, which offers new channels for the country to use its huge foreign currency reserve other than purchasing US debts. As China's contribution rate to the Asia-Pacific economy exceeds 60 percent, the huge economic potential is turning into actual influence.

As a result, the US, which used to claim that it expects China to shoulder more global responsibilities, now fears China is starting to shoulder too much in the Asia-Pacific. In an article in the New York Times, Wesley Clark, a retired four-star general and former NATO Supreme Allied Commander, said that US' constructive engagement policy toward China had failed and it is time to "get real about China".