China rebuffed U.S. pressure to curb its activity in the South China Sea on Sunday, June 5, restating its sovereignty over most of the disputed territory and saying it "has no fear of trouble".

On the last day of Asia's biggest security summit in Singapore, Admiral Sun Jianguo said China will not be bullied, including over a pending international court ruling over its claims in the vital trade route.

"We do not make trouble, but we have no fear of trouble," Sun told the Shangri-La Dialogue. "China will not bear the consequences, nor will it allow any infringement on its sovereignty and security interest, or stay indifferent to some countries creating chaos in the South China Sea."

China and the United States have traded accusations of militarising the waterway as Beijing undertakes large-scale land reclamation and construction on disputed features while Washington has increased its patrols and exercises.

On Saturday, top U.S. officials including Defense Secretary Ash Carter warned China of the risk of isolating itself internationally and pledged to remain the main guarantor of Asian security for decades.

Despite repeated notes of concern from countries such as Japan, India, Vietnam and South Korea, Sun rejected the prospect of isolation, saying that many of the Asian countries present at the Shangri-La Dialogue were "warmer" and "friendlier" to China than a year ago.

"We were not isolated in the past, we are not isolated now and we will not be isolated in the future," Sun said.

"Actually I am worried that some people and countries are still looking at China with the Cold War mentality and prejudice. They may build a wall in their minds and end up isolating themselves."

U.S. Secretary of State John Kerry urged Beijing not to establish an air defence identification zone over the South China Sea, as it did over the East China Sea in 2013.

"We would consider an ADIZ...over portions of the South China Sea as a provocative and destabilizing act which would automatically raise tensions and call into serious question China's commitment to diplomatically manage the territorial disputes of the South China Sea," Kerry said during a visit to Mongolia.

On the upcoming decision by the international tribunal in The Hague in the case brought by the Philippines to contest China's claims in the territory, Sun reiterated Beijing does not recognise the court's authority.

Sun said China wanted to solve the dispute with the Philippines bilaterally and said the door was open for dialogue with incoming President Rodrigo Duterte.

Duterte said on Thursday he would not surrender the country's rights over the disputed Scarborough Shoal in the South China Sea, which China seized in 2012.

China claims almost the entire sea. Brunei, Malaysia, the Philippines, Taiwan and Vietnam also have claims to parts of the waters, through which trillions of dollars in trade is shipped every year.

"China has the patience and wisdom to settle any disputes through dialogue. We also believe the related countries have the wisdom and patience to make peace," Sun said. "I've always believed that shaking hands is better than clenching fists."

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Vietnam's deputy Defence Minister Nguyen Chi Vinh warned of a "deteriorating trend of security" in the South China Sea.

"If not addressed timely and successfully, it is likely to entail arms race, strategic rivalry of powers with disastrous and unpredictable consequences," Vinh said.