SINGAPORE (Reuters) - The United States stepped up pressure on China on Saturday to rein in its actions in the South China Sea, with top defense officials underlining Washington’s military superiority and vowing to remain the main guarantor of Asian security for decades to come.

Defense Secretary Ash Carter said the U.S. approach to the Asia-Pacific remained “one of commitment, strength and inclusion”, but he also warned China against provocative behavior in the South China Sea.

Any action by China to reclaim land in the Scarborough Shoal, an outcrop in the disputed sea, would have consequences, Carter said.

“I hope that this development doesn’t occur, because it will result in actions being taken by the both United States and ... by others in the region which would have the effect of not only increasing tensions but isolating China,” Carter told the Shangri-La Dialogue, a regional security forum in Singapore.

“The United States will remain the most powerful military and main underwriter of security in the region for decades to come – and there should be no doubt about that.”

The South China Sea has become a flashpoint between the United States, which increased its focus on the Asia-Pacific under President Barack Obama’s “pivot”, and China, which is projecting ever greater economic, political and military power in the region.

Carter however said he would welcome China’s participation in a “principled security network” for Asia.

“Forward thinking statesmen and leaders must ... come together to ensure a positive principled future,” he said, adding that the network he envisaged could also help protect against “Russia’s worrying actions” and the growing strategic impact of climate change.

The deputy head of China’s delegation to the forum said the United States should reduce its provocative exercises and patrols in the region and said any attempts to isolate China would fail.

“This is a time of cooperation and common security,” Rear Admiral Guan Youfei told reporters. “The U.S. action to take sides is not agreed by many countries. We hope the U.S. will also listen to the other countries.”

REGIONAL WORRIES

Other Asian leaders said the situation in the South China Sea was viewed with concern across the region.

“All countries in the region need to recognize that our shared prosperities and the enviable rate of growth that this region enjoys over past decades will be put at risk by aggressive behavior or actions by any one of us,” Indian Defence Minister Manohar Parrikar told the forum.

Slideshow ( 5 images )

Japanese Defence Minister Gen Nakatani said his country would help Southeast Asian nations build their security capabilities to deal with what he called unilateral, dangerous and coercive actions in the South China Sea.

“In the South China Sea, we have been witnessing large-scale and rapid land reclamation, building of outposts and utilization of them for military purposes,” Nakatani said. “No country can be an outsider of this issue.”

A Chinese official responded by saying Japan should be careful “not to interfere and stir up problems” in the waterway, while China’s foreign ministry also weighed in regarding the U.S. and Japanese comments.

Slideshow ( 5 images )

“Counties outside the region should stick to their promises and not make thoughtless remarks about issues of territorial sovereignty,” the ministry said in a statement.

Trillions of dollars of trade a year passes through the South China Sea, which is home to rich oil, gas and fishing resources. Besides China, Vietnam, the Philippines, Malaysia, Brunei and Taiwan have claims in the area, and rising tensions have been fuelling increasing security spending in the region.

“The uncertainty of China’s future trajectory is arguably the main driving concern about possible military competition now and in the future,” Malaysian Defence Minister Hishammuddin Hussein said.

Carter said that for decades some critics had been predicting an impending U.S. withdrawal from the region, but this would not happen.

“That’s because this region, which is home to nearly half the world’s population and nearly half the global economy, remains the most consequential for America’s own security and prosperity.”

TRUMP COUNTER

In an apparent counter to “America-first” policies expounded by prospective Republican presidential candidate Donald Trump, including suggestions that U.S. troops should be withdrawn from Asia, Carter stressed bipartisan support for continued engagement.

The Shangri-La Dialogue is being held ahead of a significant ruling expected in coming weeks on a case filed by the Philippines in the International Court of Arbitration challenging China’s South China Sea claims, which Beijing has vowed to ignore.

The United States has been lobbying Asian and other countries to back the judges’ statement that their ruling must be binding, a call echoed by Japan on Saturday.

China has lobbied on the other side for support for its position that the court lacks jurisdiction in the case.