US Defence Secretary Ash Carter has urged China to join a "principled security network" for Asia, saying that the United States would remain the world's most powerful military and the main guarantor of regional security for decades to come.
In an attempt to counter concerns in Asia about US staying power, Carter told a regional security forum in Singapore the US approach to the Asia-Pacific remained "one of commitment, strength and inclusion".
However, he said, any action by China to reclaim land in the Scarborough Shoal, an outcrop in the disputed South China Sea, would have consequences.
"I hope that this development doesn't occur, because it will result in actions being taken by both the United States and ... by others in the region which would have the effect of not only increasing tensions but isolating China."
Carter said tensions in the South China Sea, where China has been backing its vast territorial claims by building artificial islands, North Korea's nuclear program and violent extremism challenged regional peace and "forward-thinking statesmen and leaders must ... come together to ensure a positive principled future".
He said the network he envisaged could also help protect against "Russia's worrying actions" and the growing strategic impact of climate change.
The US and many Asian countries were stepping up security co-operation to ensure they were able to make choices "free from coercion and intimidation", Carter said at Singapore's annual Shangri-La Dialogue.
"Even as 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 - those growing bilateral relationships demonstrate that nations around the region are also committed to doing more to promote continued regional security and prosperity," Carter said.
He stressed the work the US had undertaken to strengthen security ties with countries including Japan, India, the Philippines, Vietnam and Australia was part of President Barack Obama's so-called pivot, or rebalance, in the Asia-Pacific region.
He said that for decades some had wrongly predicted an impending US withdrawal from the region, but that 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," Carter said.