If China tries to prevent the re-supply of the grounded Philippine naval vessel BRP Sierra Madre at Ayungin Shoal, then the United States might not only offer to re-supply it, but may consider deploying a few Marines on rotation as part of training, said Patrick Cronin, senior director of the Asia-Pacific Security Program Center for a New American Security.

He said this is one of the actions the US can take to counter potential regional instability.

Testifying on America’s security role in the South China Sea at a hearing of the US House subcommittee on Asia and the Pacific on Thursday, Cronin said China’s assertiveness, its rapid military modernization and its island building program in the South China Sea directly undermined both the post-World War II order and American credibility.

“China’s use of all instruments of power and incremental salami slicing tactics are out-maneuvering the competition,” he said.

The rusting Sierra Madre, a former US Navy transport ship deliberately beached on Ayungin (Second Thomas) Shoal in 1999 and used as a marine outpost in the West Philippine Sea, is on the frontlines of an increasingly tense dispute between the Philippines and China.

Ayugin, which forms part of the Spratly island group, is being claimed in its entirety by China and in its various parts by the Philippines, Vietnam, Malaysia, Brunei and Taiwan.

Andrew Erickson, an associate professor at the China Maritime Studies Institute at the US Naval War College, said that since 2014, China has greatly accelerated its “island building” activities, developing land features in the Spratlys and Paracels that its neighbors simply cannot match.

“Features is the key word here, because many were previously small rocks or reefs not legally considered islands,” he said.

But it’s what China is constructing atop these artificial features that most concern its neighbors and the United States: militarily relevant facilities, including at least two runways capable of serving a wide range of military aircraft.

There’s no need for a 3,000-meter runway – as China now has on Woody Island in the Paracels and Kagitingan (Fiery Cross) Reef – to support evacuation of personnel for medical or weather emergencies, he said.

Such a runway is only needed to support a full range of military options. Building a separate taxiway alongside, as China has already done at Kagitingan Reef, suggests plans for high tempo, high sortie rate military operations.

Not one of the other South China Sea claimants enjoys even one runway of this caliber on any of the features that it occupies, he said.

Mira Rapp-Hooper, director of the Asia Maritime Transparency Initiative at the Center for Strategic and International Studies (CSIS), said China is the only country among the claimants to have completely transformed features formerly under water into artificial islands.

Other countries have used the technique to add some additional acreage onto features already above water.

She said a Southeast Asia Reassurance Fund proposed by the Senate Armed Services Committee with an initial budget of $50 million this year could provide much needed support to the coast guards and navies of other South China Sea claimants.

Michael Swaine of the Asia Program at the Carnegie Endowment for International Peace has called on China and the US to dial down the heated rhetoric.

Allowing a dispute over a few rocks and islands in a corner of the Asia-Pacific region to derail a vital relationship is the height of folly, he said.

Hyperbolic statements, veiled threats and calls for more military action serve no useful purpose and will only lead to hardened positions and redoubled efforts on both sides to counter the other, he added.

He claimed Washington’s message on the South China Sea issue has been badly garbled, making it sound like it is opposed to any Chinese activities that involve an increase in presence or capability in the area, with little serious reference to actions of any other claimants – particularly Vietnam and the Philippines – that China may find provocative.

This issue and the need for greater clarity regarding concerns and consequences should be addressed to justify discussion at the highest levels of government and included in the agenda when President Barack Obama meets with Xi Jinping during the Chinese leader’s state visit to Washington in September, Swaine said.

The US and China must build the basis for demilitarizing the region and defusing the escalating tensions, he said.