US Vice President Kamala Harris on Tuesday accused Beijing of continuing to "coerce" and "intimidate" in the South China Sea and pledged that Washington would pursue a free and open Indo Pacific.
Her comments came during a trip to Singapore and ahead of a visit to Vietnam, where US officials aim to reaffirm Washington's commitment to the region and address concerns about China's claims to disputed parts of the South China Sea.
"We know that Beijing continues to coerce, to intimidate and to make claims to the vast majority of the South China Sea," Harris said in a speech in Singapore.
"These unlawful claims have been rejected by the 2016 arbitral tribunal decision, and Beijing's actions continue to undermine the rules based order and threaten the sovereignty of nations," she said, referring to an international tribunal's ruling over China's claims in The Hague.
China rejected the ruling and has stood by its claim to most of the waters within a so-called Nine Dash Line, which is also contested by Brunei, Malaysia, the Philippines, Taiwan and Vietnam. China has established military outposts on artificial islands in the waters that contain gas fields and rich fishing.
The US Navy, in a show of force against the Chinese territorial claims, regularly conducts so-called "freedom of navigation" operations in which their vessels pass close by some of the contested islands. China in turn objects to the US missions, saying they do not help promote peace or stability.
The United States has put countering China at the heart of its national security policy for years and President Joe Biden's administration has called rivalry with Beijing "the biggest geopolitical test" of this century.
But a top Chinese diplomat last month accused Washington of creating an "imaginary enemy" to divert attention from domestic problems and suppress China.
Harris met on Monday with Singapore's Prime Minister Lee Hsien Loong and President Halimah Yacob during a trip aimed at bolstering ties with partners in the region as part of Washington's efforts to counter China's growing economic and security influence.
"Our partnerships in Singapore, in Southeast Asia and throughout the Indo Pacific are a top priority for the United States," Harris said on Tuesday, adding that the region "is critically important to our nation's security and prosperity".
Part of her task during the trip will be convincing leaders in the region that Washington's commitment to Southeast Asia is firm and not a parallel to Afghanistan.
US President Biden has faced criticism over his handling of the withdrawal of US forces and the chaotic evacuation after the lightning takeover by the Taliban.
Harris stressed again that the United States was "laser focused" on the task of "safely evacuating American citizens, international partners, Afghans who worked side by side with us, and other Afghans at risk".
She also said that the United States had put itself forward to host a meeting of the Asia-Pacific trade group APEC in 2023, which includes the United States, China and Japan.