The recent upsurge in tension between China and its neighbours has sparked concerns over stability in the region. And criticism from the U.S. is also raising tensions.
Five trillion dollars of ship-borne trade passes through the South China Sea each year. The wealth has attracted the scramble for the region, and China claims most of it.
On Wednesday, China said it has the will and ability to uphold its territorial sovereignty and integrity after Vietnamese and Philippine troops played soccer and sang karaoke on a South China Sea island earlier in the day.
On the same day, the recent construction of two lighthouses on Huayang Reef and Chigua Reef of China's Nansha Islands, became the subject of argument.
China says the infrastructure projects are for ordinary use to facilitate navigation and other services. The United States disagrees.
"That's why I want to be clear about our position on the South China Sea. First, we want a peaceful resolution of all disputes and an immediate and lasting halt to land reclamation by any claimant. We also oppose any further militarization of disputed features. Second, and there should be no mistake, should be no mistake about this -- the United States will fly, sail, and operate wherever international law allows, as we do all around the world. Finally, with its actions in the South China Sea, China is out of step with both international norms that underscore the Asia-Pacific security architecture and the regional consensus in favour of a non-coercive approach to this and other long-standing disputes," said Ashton Carter, US Defense Secretary.
That statement has added to the face-off between China and the U.S. with its ambition to re-engage to the Asian region.
China's Foreign Ministry has said tensions in the region were caused by countries that are playing up the tensions for their own benefit and to defame China's image.
Following Ashton Carter's statement, the topic was raised again at a press conference on Thursday.
"I want to emphasize that the US has been selectively mute on various countries' construction activities on China's islands and reefs that they have occupied, but have made irresponsible remarks on construction that is lawful, fair and reasonable within China's scope of sovereignty. The US is either using double standards or has ulterior motives. I'd like to reiterate that China's construction activities, no matter the speed or scale, match the international responsibilities and obligations of a major power of the world. The Chinese people can make their own judgement and no one has the right to tell China what to do," said Hua Chunying, spokesperson of Chinese Foreign Ministry.
The spokesperson called on all parties to develop a responsible and unbiased view of the situation, and make efforts to maintain peace and stability of the South China Sea.