U.S. Defense Secretary Jim Mattis said Saturday that one country alone should not rule the Indo-Pacific region in an apparent warning to China, criticizing Beijing's military buildup in the South China Sea.

In a speech at the Asia Security Summit in Singapore, known as the Shangri-La Dialogue, the U.S. defense chief expressed readiness to promote the "Free and Open Indo-Pacific Strategy," which is upheld by President Donald Trump's administration.

The concept is aimed at ensuring stability from East Asia to Africa through cooperation with countries that share values such as freedom of navigation and the rule of law, effectively as a strategy to counter China.

"No one nation can or should dominate the Indo-Pacific," Mattis said.

(Jim Mattis)

"China's policy in the South China Sea stands in stark contrast to the openness of our strategy," the defense chief said, adding Beijing's militarization in the contested water "is tied directly to military use for the purposes of intimidation and coercion."

"We do not ask any country to choose between the United States and China, because a friend does not demand you choose among them. China should and does have a voice in shaping the international system, and all of China's neighbors have a voice in shaping China's role," he said.

Trump's administration is also cautious about China's "One Belt, One Road" initiative of connecting countries along the ancient Silk Road more closely, saying Beijing is trying to expand its security and economic influence in Asia, the Middle East, Europe and Africa.

Washington will bolster its involvement in the Indo-Pacific region in the security and economic fields based on international rules, Mattis said, emphasizing the interests of the region are closely linked to those of the United States.

"Make no mistake, America is in the Indo-Pacific to stay," Mattis said.

Mattis, meanwhile, said, "Cooperation with China is welcome wherever possible."

(The Liaoning, Chinese aircraft carrier)
[VCG/Getty/Kyodo]

He said he will visit Beijing in the near future at China's invitation to have security dialogue.

In the South China Sea, home to some of the world's busiest sea lanes, Beijing and several Southeast Asian countries have overlapping territorial claims. It has rapidly built artificial islands with military infrastructure in the waters in recent years.

The Asian Security Summit, sponsored by the International Institute for Strategic Studies, a British think tank, has taken place every year in Singapore since 2002.

Defense officials from around 50 mainly Asian and European countries as well as the United States are participating in the three-day meeting through Sunday to exchange views on security issues in the Asia-Pacific region.

Beijing has sent a lower-ranking official, Lt. Gen. He Lei, vice president of China's Academy of Military Science, to the 2018 meeting, a move that may prevent the organizer of the event from deepening discussions on the Asian power's maritime assertiveness in the region.

He said at a press conference later Saturday that the United States has hurt China's sovereignty and security interests.