Originally Published: 27 JUL 21 09:18 ET

By Brad Lendon, CNN

(CNN) -- US Secretary of Defense Lloyd Austin said Tuesday that China's claims and actions in the Indo-Pacific threaten the sovereignty of nations around the region while Washington is committed to building partnerships that guarantee the vital interest of all nations.

"Beijing's claim to the vast majority of the South China Sea has no basis in international law. That assertion treads on the sovereignty of states in the region," Austin said in a speech to the International Institute for Strategic Studies in Singapore.

China claims almost all of the 1.3-million-square-mile South China Sea as its sovereign territory, despite much of those claims running against international law.

The US defense chief said China's intransigence extended beyond the South China Sea.

"Beijing's unwillingness to resolve disputes peacefully and respect the rule of law isn't just occurring on the water. We have also seen aggression against India, destabilizing military activity and other forms of coercion against the people of Taiwan, and genocide and crimes against humanity against Uyghur Muslims in Xinjiang," Austin said

Despite that list, Austin said the US does not seek military conflict with Beijing.

"We will not flinch when our interests are threatened. Yet we do not seek confrontation," he said.

"Let me be clear: ... I am committed to pursuing a constructive, stable relationship with China," he said.

But six months into the Biden administration, relations between Washington and Beijing, which have worsened in recent years, are rockier than ever.

The current tension was highlighted a day earlier in a war of words between senior diplomats for the two countries during talks in Tianjin, China.

A US delegation led by the Deputy Secretary of State Wendy Sherman met with Chinese Foreign Minister Wang Yi and other officials.

The State Department called the meetings "frank and open" -- diplomatic code for a skirmish -- and painted Beijing as an international outlier that is subverting international norms.

Beijing, describing the talks as "in-depth and frank," responded with a torrent of condemnation, with Chinese officials expressing "strong dissatisfaction" with Washington's "extremely dangerous China policy" and accusing it of hypocrisy on human rights.

Part of that US policy has been steadily challenging Chinese territorial claims in the South China Sea with so-called Freedom of Navigation operations, in which US warships moved through contested waters claimed by China. The US Navy also conducts regular exercises in the South China Sea.

China says the presence of the US Navy in the region is destabilizing and in the the case of the Freedom of Navigation operations, tramples on China's sovereignty.

Washington sees those operations as showing its committed to a free and open Indo-Pacific and vital to supporting US allies and partners around the region.

Austin pushed those partnerships in Tuesday's speech.

"Our network of alliances and friendships is an unparalleled strategic asset," Austin said.

"The United States and this region are more secure and more prosperous when we work together with our allies and partners," he said.

Austin said the US is not asking Indo-Pacific nations to choose between Beijing and Washington, but come together to solve regional and global problems, including the Covid-19 pandemic and climate change.

He pointed to efforts made fighting the pandemic, including Singapore's support of India with Covid relief supplies, Singapore's construction of vaccine manufacturing facilities and the United States' distribution of 40 million doses of vaccine around the region.

"They're incredibly effective at saving lives and preventing serious illness. And you know what? They're free. No conditions. No small print. And no strings attached. Because this is an emergency. And that's what friends do," Austin said.

But he also highlighted how nations around the Pacific are cooperating with the US militarily, with recent exercises including countries like Australia, Japan, South Korea and, on the day before his arrival, with host country Singapore.

In what might be the most visible display of a US-led partnership effort in the region this summer, Britain's Carrier Strike Group, led by the aircraft carrier HMS Queen Elizabeth, conducted an exercise with three ships from Singapore's Navy alongside the US and Dutch warships already in the UK-led armada. US Marine Corps fighter jets are also deployed on the British carrier, which left the UK in May and will go as far as South Korea before making its way back to Britain in the fall.

Commodore Steve Moorhouse, commander Carrier Strike Group, touted the group's presence in the region.

"The arrival of the Carrier Strike Group in Southeast Asia is a clear sign that the United Kingdom is ready to work with friends and partners, new and old, to strengthen the security and freedoms upon which we mutually depend," Moorhouse said in a statement.

Austin called the UK deployment "historic," and said it showed the partnerships not only with Washington, but among nations from within and outside the region.

"I'm especially encouraged to see our friends building stronger security ties with one another, further reinforcing the array of partnerships that keeps aggression at bay," he said.

Even before Austin arrived in Singapore on Monday, China was trying to downplay what he could accomplish during his time in Southeast Asia.

"It is easier said than done for Washington to strengthen its ties with Southeast Asia," Hu Bo, director of the Beijing-supported South China Sea Strategic Situation Probing Initiative, wrote in a piece on the state-run Global Times.

"It is difficult for Washington to leverage Southeast Asian countries in terms of economics, diplomacy, and the fight against COVID-19. The only thing Washington can offer is security and defense cooperation," Hu wrote.

"Washington has seized upon the concerns of some Southeast Asian countries about the rise of China and hyped up the 'China threat' theory, thus tightening the relations with these countries," Hu said.

Austin arrived in Singapore on Monday and in talks Tuesday with the city-state's defense minister, Ng Eng Hen, reaffirmed strong US-Singapore bilateral defense ties.

"Secretary Austin and Dr. Ng discussed the regional security environment and agreed on the importance of sustaining a rules-based order. They also agreed to continue finding ways to expand the role of the US-Singapore partnership in maintaining regional stability," the defense chiefs said in a joint statement.

Singapore hosts rotational deployments of US Navy littoral combat ships and P-8 Poseidon anti-submarine warfare aircraft. Meanwhile, it has agreed to purchase US-made F-35 stealth fighters and train its aviators and support teams on US territory, whether on the mainland or the island of Guam.

Austin's speech was made under the banner of the IISS' Fullerton Lecture and served as a replacement for one US defense secretaries give to the annual Shangri-La Dialogue, Asia's premier defense summit, which was canceled this year because of the Covid-19 pandemic.