However, Gregory B Poling, Senior Fellow for Southeast Asia and Director at the Center for Strategic and International Studies (CSIS), has said the move also has the potential to force China, which claims 90 percent of the sea, to soften its stance. Meanwhile the United States has deployed two aircraft carriers to the South China Sea for the second time in a fortnight.
Speaking earlier this week, Secretary of State Mike Pompeo branded China maritime claims across most of the key strategic waterway as “completely unlawful”.
Assistant Secretary of State David Stilwell followed up during an online forum at the Center for Strategic and International Studies by warning Beijing specifically in respect of Scarborough Shoal, an uninhabited island which is claimed by the Philippines.
He said: “Any move by the PRC [Peoples’ Republic of China] to physically occupy, reclaim, or militarise Scarborough Shoal would be a dangerous move on the part of the PRC and will have lasting and severe consequences for the PRC’s relationship with the United States as well as the entire region.”
Mr Poling, writing for the CSIS website, described the US stance as a “significant” shift.
He said: “The next time a China Coast Guard ship plays chicken with an oil rig off Vietnam or a flotilla of Chinese fishing boats appears in Indonesian waters, the United States will likely speak up more forcefully to decry the illegal action.
“And that will have a proportionately greater effect on China’s international reputation.
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“This seems especially likely amid the current pandemic, which has led Chinese diplomats to favour chest-thumping nationalism over de-escalation with its neighbours.
“But in the long term, if successfully couched within a broader policy combining pressure on Beijing and greater international coalition building to support Southeast Asian parties, it could help steer China toward a compromise that the international community could live with.
“And that ultimately is the best chance to peacefully manage the South China Sea disputes.
The USS Nimitz and USS Ronald Reagan carried out operations and military exercises in the contested waterway between July 4 and July 6, and returned to the region yesterday, according to a US Navy statement.
Rear Admiral Jim Kirk, commander of the Nimitz, said: “Nimitz and Reagan Carrier Strike Groups are operating in the South China Sea, wherever international law allows, to reinforce our commitment to a free and open Indo-Pacific, a rules based international order, and to our allies and partners in the region.”
The presence of the carriers was not in response to political or world events, the statement insisted.
China held military drills in the sea earlier this month, prompting condemnation from both Vietnam and the Philippines, at the same time as the two carriers first crossed the waterway for what the US Navy said were pre-planned exercises.
Roughly £2.4trillion ($3trillion) of trade passes through the South China Sea each year.
The United States has accused China of trying to intimidate Asian neighbours who might want to exploit its extensive oil and gas reserves.