U.S defence secretary
US will take action against China for fresh South China Sea construction Pictured: U.S Defence Secretary Ashton Carter speaks during a press conference in London on Oct. 9 2015.Reuters

The U.S. on Saturday warned China over constructing in an islet claimed by Philippines in the South China Sea. The move would force action by the U.S. and other countries if China were to go through with the construction, U.S. Defence Secretary Ashton Carter said at the Asia Security Summit in Singapore on Saturday.

Carter also said that China runs the risk of creating a "Great Wall of self-isolation" because of its aggressive takeover of the South China Sea, an area that facilitates maritime trade worth $5 trillion.

"I hope that this development doesn't occur because it will result in actions being taken both by the United States, and actions being taken by others in the region that will have the effect of not only increasing tensions but isolating China," Carter was quoted as saying by Agence France Presse about Scarborough Shoal, the islet in question.

The shoal, Manila says, belongs inside its exclusive economic zone. But, China reportedly is constructing an outpost there.

"America wants to expand military-to-military agreements with China to focus not only on risk reduction, but also on practical cooperation," Carter said.

The event was also attended by top Chinese military officials.

U.S.' move is believed to be part of its Asia "rebalance" policy that the U.S. believes would help the western country's long-term economic interests.

The Philippines, Brunei, Malaysia and Vietnam have also claimed land in the Spratly Islands in South China Sea, and the U.S. is an ally to them. The U.S. had conducted freedom of navigation exercises in the region, which China urged them to stop. China also told the U.S. to not decide its policy on the South China Sea issue based on its allies interests.