Carrier strike groups Theodore Roosevelt and Nimitz carried out multiple manoeuvres in the busy resource-rich waterway.
China has drilled deep in the South China Sea to retrieve sediment core from the seabed, state media has reported, amid tensions over disputed waters with rival claimants Taiwan and the Philippines, as the United States increases its naval presence in the region.
Chinese scientists on a marine research vessel used China’s homemade Sea Bull II drilling system to obtain a sediment core 231 metres (757 feet) long at a depth of 2,060m (6,760ft), according to the official Xinhua news agency on Thursday.
The system can help explore natural gas hydrate resources in the seabed, Xinhua added, referring to the solid ice-like crystals formed from a mixture of methane and water that are touted as a promising source of energy.
It was unclear exactly where the drilling took place in the South China Sea, approximately 90 percent of which is claimed by Beijing as its territorial waters. The International Court of Arbitration at The Hague has declared that claim as without legal basis.
Malaysia, the Philippines, Taiwan, Vietnam and Brunei also lay claim to parts of the sea, which has vast oil and gas potential.
Tensions in the region have escalated in recent weeks following revelations that 200 Chinese “maritime militia” vessels have been amassing at Whitsun Reef, about 320 kilometres (200 miles) west of Palawan Island and within the Philippines’s exclusive economic zone (EEZ).
Since then, the US has deployed a Navy strike group led by the USS Theodore Roosevelt, which entered the South China Sea on Sunday.
According to a South China Morning Post newspaper report on Friday, the US has also deployed the amphibious assault ship USS Makin Island to enter the busy sea lane through the Strait of Malacca.
The group also reportedly included the amphibious transport dock USS San Diego, the publication reported, citing information from the Beijing-based South China Sea Strategic Situation Probing Initiative.
The US has defended its latest naval activities calling it a “routine” transit and in accordance with the “freedom of navigation” principle.
On Friday, it was also reported that Chinese military vessels gave chase on Thursday to a Filipino vessel with civilians and journalists on board with the Philippines’ EEZ, according to the Manila-based television station, ABS-CBN.
The Philippines, a US ally that has developed closer ties with Beijing since the administration of President Rodrigo Duterte, has voiced concern in recent days about the presence of Chinese vessels in its EEZ.
On Thursday, the Philippine defence department said it was keeping “all our options open” as Manila’s diplomatic dispute with Beijing grows.
“As the situation (in the South China Sea) evolves, we keep all our options open in managing the situation, including leveraging our partnerships with other nations such as the United States,” Philippine defence department spokesman Arsenio Andolong said on Thursday.
The Department of Foreign Affairs has also pledged to file a diplomatic protest daily until the Chinese vessels leave the Whitsun Reef.
Self-ruled Taiwan, which China claims as its own territory, has also threatened to shoot down Chinese drones spotted circling the Taipei-controlled Pratas Islands in the South China Sea.
In recent days, tensions in the Taiwan Straits have also grown, with the self-governing democractic island reporting on Wednesday that 15 more of the mainland’s planes crossed into Taiwan’s air defence zone.
Taipei warned that it would defend itself “to the very last day” if necessary.
THREAD: following reports of PLA Navy Type-022 Houbei catamaran missile fast attack craft harassing a motorboat chartered by ABS-CBN journalists in the Spratlys, Beijing's pretense about just using "white hulls" to promote SCS peace and stability is well over. Context is impt. pic.twitter.com/F8bwN7Fmr0
— Collin Koh (@CollinSLKoh) April 9, 2021
On Monday the Chinese carrier, Liaoning, also led a naval exercise near Taiwan and Beijing said that such drills will become regular occurrences.
China’s oil and gas exploration activities in the South China Sea have stoked tensions before, notably when state-run China National Offshore Oil Corp (CNOOC) deployed a deepwater drilling rig in Vietnam-claimed waters in 2014.
One-third of the world’s trade estimated at more than $3 trillion passes through the South China Sea annually.